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      Open Publication Structure (OPS) 2.0 v1.0
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      <p class="Title">
        Open Publication Structure (OPS) 2.0 v<del>0.987</del><ins>1.0</ins>
      </p>

      <p class="Status">
        Recommended Specification <del>July 11, 2007</del><ins>September 11, 2007</ins>
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      <p class="Copyright">
        Copyright © 2007 by International Digital Publishing Forum™.
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        All rights reserved. This work is protected under Title 17 of the United States Code.
        Reproduction and dissemination of this work with changes is prohibited except with the
        written permission of the International Digital Publishing Forum.
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    <div class="TOC">
      <p class="TOCTitle">
        Table of Contents
      </p>

      <div class="TOCSection">
        <p class="TOCItem">
          <a class="TOC"
             href="#Section1.0"
             id="TOC1.0"
             name="TOC1.0">1.0: Overview</a>
        </p>

        <p class="TOCItem2">
          <a class="TOC"
             href="#Section1.1"
             id="TOC1.1"
             name="TOC1.1">1.1: Purpose and Scope</a>
        </p>

        <p class="TOCItem2">
          <a class="TOC"
             href="#Section1.2"
             id="TOC1.2"
             name="TOC1.2">1.2: Definitions</a>
        </p>

        <p class="TOCItem2">
          <a class="TOC"
             href="#Section1.3"
             id="TOC1.3"
             name="TOC1.3">1.3: Relationship to Other Specifications</a>
        </p>

        <p class="TOCItem3">
          <a class="TOC"
             href="#Section1.3.1"
             id="TOC1.3.1"
             name="TOC1.3.1">1.3.1: Relationship to XML</a>
        </p>

        <p class="TOCItem3">
          <a class="TOC"
             href="#Section1.3.2"
             id="TOC1.3.2"
             name="TOC1.3.2">1.3.2: Relationship to XML Namespaces</a>
        </p>

        <p class="TOCItem3">
          <a class="TOC"
             href="#Section1.3.3"
             id="TOC1.3.3"
             name="TOC1.3.3">1.3.3: Relationship to NVDL</a>
        </p>

        <p class="TOCItem3">
          <a class="TOC"
             href="#Section1.3.4"
             id="TOC1.3.4"
             name="TOC1.3.4">1.3.4: Relationship to XHTML and DTBook</a>
        </p>

        <p class="TOCItem3">
          <a class="TOC"
             href="#Section1.3.5"
             id="TOC1.3.5"
             name="TOC1.3.5">1.3.5: Relationship to CSS</a>
        </p>

        <p class="TOCItem3">
          <a class="TOC"
             href="#Section1.3.6"
             id="TOC1.3.6"
             name="TOC1.3.6">1.3.6: Relationship to Unicode</a>
        </p>

        <p class="TOCItem3">
          <a class="TOC"
             href="#Section1.3.7"
             id="TOC1.3.7"
             name="TOC1.3.7">1.3.7: MIME Media Types</a>
        </p>

        <p class="TOCItem3">
          <a class="TOC"
             href="#Section1.3.8"
             id="TOC1.3.8"
             name="TOC1.3.8">1.3.8: XML Style Sheet Processing Instruction</a>
        </p>

        <p class="TOCItem2">
          <a class="TOC"
             href="#Section1.4"
             id="TOC1.4"
             name="TOC1.4">1.4: Conformance</a>
        </p>

        <p class="TOCItem3">
          <a class="TOC"
             href="#Section1.4.1"
             id="TOC1.4.1"
             name="TOC1.4.1">1.4.1: OPS Content Document Conformance</a>
        </p>

        <p class="TOCItem4">
          <a class="TOC"
             href="#Section1.4.1.1"
             id="TOC1.4.1.1"
             name="TOC1.4.1.1">1.4.1.1: OPS Content Document</a>
        </p>

        <p class="TOCItem4">
          <a class="TOC"
             href="#Section1.4.1.2"
             id="TOC1.4.1.2"
             name="TOC1.4.1.2">1.4.1.2: XHTML <ins>Content</ins> Document Requirements</a>
        </p>

        <p class="TOCItem4">
          <a class="TOC"
             href="#Section1.4.1.3"
             id="TOC1.4.1.3"
             name="TOC1.4.1.3">1.4.1.3: DTBook Content Document Requirements</a>
        </p>

        <p class="TOCItem4">
          <a class="TOC"
             href="#Section1.4.1.4"
             id="TOC1.4.1.4"
             name="TOC1.4.1.4">1.4.1.4: Out-of-Line XML Island Content Document Requirements</a>
        </p>

        <p class="TOCItem3">
          <a class="TOC"
             href="#Section1.4.2"
             id="TOC1.4.2"
             name="TOC1.4.2">1.4.2: Reading System Conformance</a>
        </p>

        <p class="TOCItem3">
          <a class="TOC"
             href="#Section1.4.3"
             id="TOC1.4.3"
             name="TOC1.4.3">1.4.3: Compatibility with Future Versions</a>
        </p>

        <p class="TOCItem3">
          <a class="TOC"
             href="#Section1.4.4"
             id="TOC1.4.4"
             name="TOC1.4.4">1.4.4: Compatibility of OPS Version 2.0</a>
        </p>

        <p class="TOCItem2">
          <a class="TOC"
             href="#Section1.5"
             id="TOC1.5"
             name="TOC1.5">1.5: Extensibility</a>
        </p>

        <p class="TOCItem2">
          <a class="TOC"
             href="#Section1.6"
             id="TOC1.6"
             name="TOC1.6">1.6: Accessibility</a>
        </p>

        <p class="TOCItem2">
          <a class="TOC"
             href="#Section1.7"
             id="TOC1.7"
             name="TOC1.7">1.7: Future Directions</a>
        </p>
      </div>

      <div class="TOCSection">
        <p class="TOCItem">
          <a class="TOC"
             href="#Section2.0"
             id="TOC2.0"
             name="TOC2.0">2.0: OPS Content Document Vocabularies</a>
        </p>

        <p class="TOCItem2">
          <a class="TOC"
             href="#Section2.1"
             id="TOC2.1"
             name="TOC2.1">2.1: Introduction</a>
        </p>

        <p class="TOCItem2">
          <a class="TOC"
             href="#Section2.2"
             id="TOC2.2"
             name="TOC2.2">2.2: XHTML Modules in the OPS Preferred Vocabulary</a>
        </p>

        <p class="TOCItem3">
          <a class="TOC"
             href="#Section2.2.1"
             id="TOC2.2.1"
             name="TOC2.2.1">2.2.1: Required Modules</a>
        </p>

        <p class="TOCItem2">
          <a class="TOC"
             href="#Section2.3"
             id="TOC2.3"
             name="TOC2.3">2.3: Certain Element and Attribute Semantic Differences From, and
             Restrictions Beyond, XHTML 1.1</a>
        </p>

        <p class="TOCItem3">
          <a class="TOC"
             href="#Section2.3.1"
             id="TOC2.3.1"
             name="TOC2.3.1">2.3.1: General Comments on URI References</a>
        </p>

        <p class="TOCItem3">
          <a class="TOC"
             href="#Section2.3.2"
             id="TOC2.3.2"
             name="TOC2.3.2">2.3.2: <span class="Element">body</span> Element</a>
        </p>

        <p class="TOCItem3">
          <a class="TOC"
             href="#Section2.3.3"
             id="TOC2.3.3"
             name="TOC2.3.3">2.3.3: <span class="Attribute">cite</span> Attribute</a>
        </p>

        <p class="TOCItem3">
          <a class="TOC"
             href="#Section2.3.4"
             id="TOC2.3.4"
             name="TOC2.3.4">2.3.4: <span class="Element">img</span> Element</a>
        </p>

        <p class="TOCItem3">
          <a class="TOC"
             href="#Section2.3.5"
             id="TOC2.3.5"
             name="TOC2.3.5">2.3.5: <span class="Element">link</span> Element</a>
        </p>

        <p class="TOCItem3">
          <a class="TOC"
             href="#Section2.3.6"
             id="TOC2.3.6"
             name="TOC2.3.6">2.3.6: <span class="Element">object</span> and <span class=
             "Element">param</span> Elements</a>
        </p>

        <p class="TOCItem3">
          <a class="TOC"
             href="#Section2.3.7"
             id="TOC2.3.7"
             name="TOC2.3.7">2.3.7: <span class="Element">script</span> and <span class=
             "Element">noscript</span> Elements</a>
        </p>

        <p class="TOCItem3">
          <a class="TOC"
             href="#Section2.3.8"
             id="TOC2.3.8"
             name="TOC2.3.8">2.3.8: <span class="Attribute">type</span> attribute of the
             <span class="Element">style</span> element</a>
        </p>

        <p class="TOCItem3">
          <a class="TOC"
             href="#Section2.3.9"
             id="TOC2.3.9"
             name="TOC2.3.9">2.3.9: Value of <span class="Attribute">align</span> attribute</a>
        </p>

        <p class="TOCItem2">
          <a class="TOC"
             href="#Section2.4"
             id="TOC2.4"
             name="TOC2.4">2.4: DTBook Preferred Vocabulary</a>
        </p>

        <p class="TOCItem3">
          <a class="TOC"
             href="#Section2.4.1"
             id="TOC2.4.1"
             name="TOC2.4.1">2.4.1: Introduction</a>
        </p>

        <p class="TOCItem3">
          <a class="TOC"
             href="#Section2.4.2"
             id="TOC2.4.2"
             name="TOC2.4.2">2.4.2: DTBook Usage Requirements</a>
        </p>

        <p class="TOCItem4">
          <a class="TOC"
             href="#Section2.4.2.1"
             id="TOC2.4.2.1"
             name="TOC2.4.2.1">2.4.2.1: Exceptions to Section 4 of the DAISY/NISO Standard</a>
        </p>

        <p class="TOCItem2">
          <a class="TOC"
             href="#Section2.5"
             id="TOC2.5"
             name="TOC2.5">2.5: SVG</a>
        </p>

        <p class="TOCItem3">
          <a class="TOC"
             href="#Section2.5.1"
             id="TOC2.5.1"
             name="TOC2.5.1">2.5.1: General Notes on SVG Usage</a>
        </p>

        <p class="TOCItem3">
          <a class="TOC"
             href="#Section2.5.2"
             id="TOC2.5.2"
             name="TOC2.5.2">2.5.2: SVG’s Use as a Standalone Image File</a>
        </p>

        <p class="TOCItem3">
          <a class="TOC"
             href="#Section2.5.3"
             id="TOC2.5.3"
             name="TOC2.5.3">2.5.3: Mixing SVG and XHTML Mark-up in the Same Document</a>
        </p>

        <p class="TOCItem2">
          <a class="TOC"
             href="#Section2.6"
             id="TOC2.6"
             name="TOC2.6">2.6: XML Islands</a>
        </p>

        <p class="TOCItem3">
          <a class="TOC"
             href="#Section2.6.1"
             id="TOC2.6.1"
             name="TOC2.6.1">2.6.1: Introduction to XML Islands</a>
        </p>

        <p class="TOCItem4">
          <a class="TOC"
             href="#Section2.6.1.1"
             id="TOC2.6.1.1"
             name="TOC2.6.1.1">2.6.1.1: Use Cases</a>
        </p>

        <p class="TOCItem4">
          <a class="TOC"
             href="#Section2.6.1.2"
             id="TOC2.6.1.2"
             name="TOC2.6.1.2">2.6.1.2: Display Guidelines</a>
        </p>

        <p class="TOCItem3">
          <a class="TOC"
             href="#Section2.6.2"
             id="TOC2.6.2"
             name="TOC2.6.2">2.6.2: Out-of-Line XML Islands</a>
        </p>

        <p class="TOCItem4">
          <a class="TOC"
             href="#Section2.6.2.1"
             id="TOC2.6.2.1"
             name="TOC2.6.2.1">2.6.2.1: Document Requirements</a>
        </p>

        <p class="TOCItem4">
          <a class="TOC"
             href="#Section2.6.2.2"
             id="TOC2.6.2.2"
             name="TOC2.6.2.2">2.6.2.2: Fallback Requirements</a>
        </p>

        <p class="TOCItem4">
          <a class="TOC"
             href="#Section2.6.2.3"
             id="TOC2.6.2.3"
             name="TOC2.6.2.3">2.6.2.3: Linking Requirements</a>
        </p>

        <p class="TOCItem5">
          <a class="TOC"
             href="#Section2.6.2.3.1"
             id="TOC2.6.2.3.1"
             name="TOC2.6.2.3.1">2.6.2.3.1: Document-Level Links</a>
        </p>

        <p class="TOCItem5">
          <a class="TOC"
             href="#Section2.6.2.3.2"
             id="TOC2.6.2.3.2"
             name="TOC2.6.2.3.2">2.6.2.3.2: Fragment Links</a>
        </p>

        <p class="TOCItem3">
          <a class="TOC"
             href="#Section2.6.3"
             id="TOC2.6.3"
             name="TOC2.6.3">2.6.3: Inline XML Islands</a>
        </p>

        <p class="TOCItem4">
          <a class="TOC"
             href="#Section2.6.3.1"
             id="TOC2.6.3.1"
             name="TOC2.6.3.1">2.6.3.1: The <span class="Element">switch</span> Element and
             Contained Elements</a>
        </p>

        <p class="TOCItem5">
          <a class="TOC"
             href="#Section2.6.3.1.1"
             id="TOC2.6.3.1.1"
             name="TOC2.6.3.1.1">2.6.3.1.1: <span class="Element">switch</span> Element</a>
        </p>

        <p class="TOCItem5">
          <a class="TOC"
             href="#Section2.6.3.1.2"
             id="TOC2.6.3.1.2"
             name="TOC2.6.3.1.2">2.6.3.1.2: <span class="Element">case</span> Element</a>
        </p>

        <p class="TOCItem6">
          <a class="TOC"
             href="#Section2.6.3.1.2.1"
             id="TOC2.6.3.1.2.1"
             name="TOC2.6.3.1.2.1">2.6.3.1.2.1: <span class="Attribute">required-namespace</span>
             Attribute</a>
        </p>

        <p class="TOCItem6">
          <a class="TOC"
             href="#Section2.6.3.1.2.2"
             id="TOC2.6.3.1.2.2"
             name="TOC2.6.3.1.2.2">2.6.3.1.2.2: <span class="Attribute">required-modules</span>
             attribute</a>
        </p>

        <p class="TOCItem5">
          <a class="TOC"
             href="#Section2.6.3.1.3"
             id="TOC2.6.3.1.3"
             name="TOC2.6.3.1.3">2.6.3.1.3: <span class="Element">default</span> Element</a>
        </p>

        <p class="TOCItem4">
          <a class="TOC"
             href="#Section2.6.3.2"
             id="TOC2.6.3.2"
             name="TOC2.6.3.2">2.6.3.2: Processing Inline XML Islands</a>
        </p>

        <p class="TOCItem4">
          <a class="TOC"
             href="#Section2.6.3.3"
             id="TOC2.6.3.3"
             name="TOC2.6.3.3">2.6.3.3: Displaying Inline XML Islands</a>
        </p>

        <p class="TOCItem5">
          <a class="TOC"
             href="#Section2.6.3.3.1"
             id="TOC2.6.3.3.1"
             name="TOC2.6.3.3.1">2.6.3.3.1: Advanced Display Semantics</a>
        </p>

        <p class="TOCItem5">
          <a class="TOC"
             href="#Section2.6.3.3.2"
             id="TOC2.6.3.3.2"
             name="TOC2.6.3.3.2">2.6.3.3.2: Styling of Islands</a>
        </p>

        <p class="TOCItem4">
          <a class="TOC"
             href="#Section2.6.3.4"
             id="TOC2.6.3.4"
             name="TOC2.6.3.4">2.6.3.4: Linking Considerations</a>
        </p>

        <p class="TOCItem5">
          <a class="TOC"
             href="#Section2.6.3.4.1"
             id="TOC2.6.3.4.1"
             name="TOC2.6.3.4.1">2.6.3.4.1: Linking to <span class="Element">switch</span>
             Elements</a>
        </p>

        <p class="TOCItem5">
          <a class="TOC"
             href="#Section2.6.3.4.2"
             id="TOC2.6.3.4.2"
             name="TOC2.6.3.4.2">2.6.3.4.2: Broken Links</a>
        </p>

        <p class="TOCItem4">
          <a class="TOC"
             href="#Section2.6.3.5"
             id="TOC2.6.3.5"
             name="TOC2.6.3.5">2.6.3.5: NCX Requirements</a>
        </p>

        <p class="TOCItem2">
          <a class="TOC"
             href="#Section2.7"
             id="TOC2.7"
             name="TOC2.7">2.7: Rendering of Documents on Reading Systems</a>
        </p>
      </div>

      <div class="TOCSection">
        <p class="TOCItem">
          <a class="TOC"
             href="#Section3.0"
             id="TOC3.0"
             name="TOC3.0">3.0: OPS Style Sheets</a>
        </p>

        <p class="TOCItem2">
          <a class="TOC"
             href="#Section3.1"
             id="TOC3.1"
             name="TOC3.1">3.1: Selectors</a>
        </p>

        <p class="TOCItem2">
          <a class="TOC"
             href="#Section3.2"
             id="TOC3.2"
             name="TOC3.2">3.2: Value Types</a>
        </p>

        <p class="TOCItem3">
          <a class="TOC"
             href="#Section3.2.1"
             id="TOC3.2.1"
             name="TOC3.2.1">3.2.1: URI Values</a>
        </p>

        <p class="TOCItem3">
          <a class="TOC"
             href="#Section3.2.2"
             id="TOC3.2.2"
             name="TOC3.2.2">3.2.2: Integers and Real Numbers</a>
        </p>

        <p class="TOCItem3">
          <a class="TOC"
             href="#Section3.2.3"
             id="TOC3.2.3"
             name="TOC3.2.3">3.2.3: Length</a>
        </p>

        <p class="TOCItem3">
          <a class="TOC"
             href="#Section3.2.4"
             id="TOC3.2.4"
             name="TOC3.2.4">3.2.4: Percentages</a>
        </p>

        <p class="TOCItem3">
          <a class="TOC"
             href="#Section3.2.5"
             id="TOC3.2.5"
             name="TOC3.2.5">3.2.5: Color</a>
        </p>

        <p class="TOCItem3">
          <a class="TOC"
             href="#Section3.2.6"
             id="TOC3.2.6"
             name="TOC3.2.6">3.2.6: Time</a>
        </p>

        <p class="TOCItem3">
          <a class="TOC"
             href="#Section3.2.7"
             id="TOC3.2.7"
             name="TOC3.2.7">3.2.7: Frequency</a>
        </p>

        <p class="TOCItem3">
          <a class="TOC"
             href="#Section3.2.8"
             id="TOC3.2.8"
             name="TOC3.2.8">3.2.8: Strings</a>
        </p>

        <p class="TOCItem2">
          <a class="TOC"
             href="#Section3.3"
             id="TOC3.3"
             name="TOC3.3">3.3: Properties</a>
        </p>

        <p class="TOCItem2">
          <a class="TOC"
             href="#Section3.4"
             id="TOC3.4"
             name="TOC3.4">3.4: Embedded Fonts</a>
        </p>
      </div>

      <div class="TOCSection">
        <p class="TOCItem">
          <a class="TOC"
             href="#AppendixA"
             id="AppendixTOCA"
             name="AppendixTOCA">Appendix A: The NVDL Definition of OPS <ins>XHTML Content
             Documents</ins></a>
        </p>
      </div>

      <div class="TOCSection">
        <p class="TOCItem">
          <a class="TOC"
             href="#AppendixB"
             id="AppendixTOCB"
             name="AppendixTOCB">Appendix B: The OPS Schema</a>
        </p>
      </div>

      <div class="TOCSection">
        <p class="TOCItem">
          <a class="TOC"
             href="#AppendixC"
             id="AppendixTOCC"
             name="AppendixTOCC">Appendix C: Contributors</a>
        </p>
      </div>

      <div class="TOCSection">
        <p class="TOCItem">
          <a class="TOC"
             href="#AppendixD"
             id="AppendixTOCD"
             name="AppendixTOCD">Appendix D: Acknowledgements</a>
        </p>
      </div>

      <div class="TOCSection">
        <p class="TOCItem">
          <a class="TOC"
             href="#AppendixE"
             id="AppendixTOCE"
             name="AppendixTOCE"><ins>Appendix E: Supporting Information &amp; Errata</ins></a>
        </p>
      </div>
    </div>

    <div class="Body">
      <div class="Section">
        <h1 class="SectionTitle">
          <a class="SectionTitle"
              href="#TOC1.0"
              id="Section1.0"
              name="Section1.0">1.0: Overview</a>
        </h1>

        <div class="Section">
          <h2 class="SubsectionTitle">
            <a class="SectionTitle"
                href="#TOC1.1"
                id="Section1.1"
                name="Section1.1">1.1: Purpose and Scope</a>
          </h2>

          <p class="Copy">
            In order for electronic-book technology to achieve widespread success in the
            marketplace, Reading Systems need to have convenient access to a large number and
            variety of titles. The Open Publication Structure (OPS) Specification describes a
            standard for representing the content of electronic publications. Specifically:
          </p>

          <ul>
            <li>The specification is intended to give content providers (e.g. publishers, authors,
            and others who have content to be displayed) and publication tool providers, minimal
            and common guidelines that ensure fidelity, accuracy, accessibility, and adequate
            presentation of electronic content over various Reading Systems.
            </li>

            <li>The specification seeks to reflect established content format standards.
            </li>

            <li>The goal of this specification is to define a standard means of content description
            for use by purveyors of electronic books (publishers, agents, authors et al.) allowing
            such content to be provided to multiple Reading Systems and to insure maximum
            presentational equivalence across Reading Systems.
            </li>
          </ul>

          <p class="Copy">
            Another related specification, the Open Packaging Format (OPF) Specification, defines
            the mechanism by which the various components of an OPS publication are tied together
            and provides additional structure and semantics to the electronic publication.
            Specifically, OPF:
          </p>

          <ul>
            <li>Describes and references all components of the electronic publication (e.g. markup
            files, images, navigation structures).
            </li>

            <li>Provides publication-level metadata.
            </li>

            <li>Specifies the linear reading-order of the publication.
            </li>

            <li>Provides fallback information for when extensions to OPS are employed.
            </li>

            <li>Provides a mechanism to specify a declarative table of contents (the NCX).
            </li>
          </ul>

          <p class="Copy">
            The OPF specification is separated from this OPS markup specification to modularize the
            described packaging methodology separate from the described content. This will help
            facilitate the use of the packaging technology by other standards bodies (e.g.
            <del>Daisy</del><ins>DAISY</ins>) in non-OPS contexts.
          </p>

          <p class="Copy">
            A third specification, the OEBPS Container Format (OCF) Specification, defines the
            standard mechanism by which all components of an electronic publication may be packaged
            together into a single archive for transmission, delivery and archival purposes.
          </p>
        </div>

        <div class="Section">
          <h2 class="SubsectionTitle">
            <a class="SectionTitle"
                href="#TOC1.2"
                id="Section1.2"
                name="Section1.2">1.2: Definitions</a>
          </h2>

          <div class="DefinitionList">
            <p class="DefinitionName">
              Content Provider
            </p>

            <p class="DefinitionCopy">
              A publisher, author, or other information provider who provides a publication to one
              or more Reading Systems in the form described in this specification.
            </p>

            <p class="DefinitionName">
              Deprecated
            </p>

            <p class="DefinitionCopy">
              A feature that is permitted, but not <span class="RFC">recommended</span>, by this
              specification. Such features might be removed in future revisions. Conformant Reading
              Systems <span class="RFC">must</span> support deprecated features.
            </p>

            <p class="DefinitionName">
              Extended Module
            </p>

            <p class="DefinitionCopy">
              A module of a modularized XML vocabulary (i.e. a set of named modules is defined in
              its specification) that is not required to be supported by its specification (e.g.
              the XHTML ruby or forms modules in the OPS context).
            </p>

            <p class="DefinitionName">
              Inline XML Island
            </p>

            <p class="DefinitionCopy">
              An Inline XML Island is an XML document fragment using a non-Preferred Vocabulary or
              using an Extended Module that exists within an XHTML Preferred Vocabulary document
              within an OPS Publication.
            </p>

            <p class="DefinitionName">
              <ins>NCX</ins>
            </p>

            <p class="DefinitionCopy">
              <ins>A declarative table of contents (the Navigation Center eXtended or NCX).</ins>
            </p>

            <p class="DefinitionName">
              NVDL
            </p>

            <p class="DefinitionCopy">
              NVDL (<span class="FormalName">Namespace-based Validation Dispatching
              Language</span>) is a specification which allows for cross-schema validation of
              documents. This specification uses the NVDL language as a means of unambiguously
              defining how various schemas are handled within the context of OPS.
            </p>

            <p class="DefinitionName">
              OCF
            </p>

            <p class="DefinitionCopy">
              The OEBPS Container Format defines a mechanism by which all components of an OPS
              Publication may be combined into a single file-system entity.
            </p>

            <p class="DefinitionName">
              OEBPS
            </p>

            <p class="DefinitionCopy">
              The Open eBook Publication Structure. Previous versions of this specification (OPS)
              and its related specification, OPF, were unified into the single OEBPS specification.
              For this version, OEBPS was broken into OPS and OPF to aid modular adoption of the
              specifications. OEBPS 1.2 was the highest version of the previous unified
              specification.
            </p>

            <p class="DefinitionName">
              OPF
            </p>

            <p class="DefinitionCopy">
              The Open Packaging Format is the sister-standard to this standard. It defines the
              mechanism by which all components of a published work conforming to this standard
              along with metadata, reading order and navigational information are packaged into an
              OPS Publication.
            </p>

            <p class="DefinitionName">
              OPF Package Document
            </p>

            <p class="DefinitionCopy">
              An XML document that describes an OPS Publication and references all files used by
              the OPS Publication that are not part of the OPF Package Document itself. It
              identifies all other files in the publication and provides descriptive information
              about them. The OPF Package Document is defined by the <a href=
              "http://www.idpf.org/opf/opf2.0/download/"
                 target="_blank"
                 title="The OPF Specification">OPF Specification</a>.
            </p>

            <p class="DefinitionName">
              OPS
            </p>

            <p class="DefinitionCopy">
              The Open Publication Structure — this standard.
            </p>

            <p class="DefinitionName">
              OPS Content Document
            </p>

            <p class="DefinitionCopy">
              An XHTML, DTBook, or Out-Of-Line XML Island that conforms to this specification that
              may legally appear in an OPF Package Document <span class="Element">spine</span>
              element.
            </p>

            <p class="DefinitionName">
              OPS Core Media Type
            </p>

            <p class="DefinitionCopy">
              A MIME media type that all Reading Systems <span class="RFC">must</span> support.
            </p>

            <p class="DefinitionName">
              OPS Publication
            </p>

            <p class="DefinitionCopy">
              A collection of OPS Content Documents, an OPF Package Document, and other files,
              typically in a variety of media types, including structured text and graphics, that
              constitute a cohesive unit for publication.
            </p>

            <p class="DefinitionName">
              Out-of-Line XML Island
            </p>

            <p class="DefinitionCopy">
              An Out-of-Line XML Island is an XML document, which exists within an OPS Publication,
              and is either not authored using a Preferred Vocabulary or is authored using a
              Preferred Vocabulary but uses Extended Modules. It is an entirely separate, complete,
              and valid XML document.
            </p>

            <p class="DefinitionName">
              Preferred Vocabulary
            </p>

            <p class="DefinitionCopy">
              XML consisting only of OPS-supported XHTML modules and/or DTBook markup.
            </p>

            <p class="DefinitionName">
              Reader
            </p>

            <p class="DefinitionCopy">
              A person who reads a publication.
            </p>

            <p class="DefinitionName">
              Reading Device
            </p>

            <p class="DefinitionCopy">
              The physical platform (hardware and software) on which publications are rendered.
            </p>

            <p class="DefinitionName">
              Reading System
            </p>

            <p class="DefinitionCopy">
              A combination of hardware and/or software that accepts OPS Publications (preferably
              packaged in an OCF Container) and makes them available to consumers of the content.
              Great variety is possible in the architecture of Reading Systems. A Reading System
              <span class="RFC">may</span> be implemented entirely on one device, or it
              <span class="RFC">may</span> be split among several computers. In particular, a
              Reading Device that is a component of a Reading System <span class="RFC">need
              not</span> directly accept OPS Publications, but all Reading Systems <span class=
              "RFC">must</span> do so. Reading Systems <span class="RFC">may</span> include
              additional processing functions, such as compression, indexing, encryption, rights
              management, and distribution.
            </p>

            <p class="DefinitionName">
              XML Document
            </p>

            <p class="DefinitionCopy">
              An XML document is a complete and valid XML document as defined by XML 1.1 standard.
              (<a href="http://www.w3.org/TR/xml11/"
                 target="_blank"
                 title="XML 1.1 Specification">http://www.w3.org/TR/xml11/</a>).
            </p>

            <p class="DefinitionName">
              XML Document Fragment
            </p>

            <p class="DefinitionCopy">
              Referred to as either a document fragment or as an XML Document Fragment, as defined
              in Document Object Model Level 1 (<a href="http://www.w3.org/TR/REC-DOM-Level-1/"
                 target="_blank"
                 title="DOM Level 1 Specification">http://www.w3.org/TR/REC-DOM-Level-1/</a>) but
                 with the additional requirement that they be well-formed.
            </p>

            <p class="DefinitionName">
              XML Island
            </p>

            <p class="DefinitionCopy">
              An Inline XML Island or an Out-of-Line XML Island.
            </p>

            <p class="DefinitionName">
              XML Namespaces
            </p>

            <p class="DefinitionCopy">
              Referred to as XML namespaces, or just namespaces, these must conform to XML
              Namespaces (<a href="http://www.w3.org/TR/xml-names11/"
                 target="_blank"
                 title="The XML Namespaces Specification">http://www.w3.org/TR/xml-names11/</a>).
            </p>

            <p class="DefinitionName">
              <del>XPointer</del>
            </p>

            <p class="DefinitionCopy">
              <del>The XML Pointer Framework is a W3C specification that defines a method of
              pointing into specific locations within an XML document, thus identifying document
              fragments, as defined in XML Pointer Framework (<a href=
              "http://www.w3.org/TR/xptr-framework/"
                 target="_blank"
                 title=
                 "The XML Pointer Framework specification.">http://www.w3.org/TR/xptr-framework/</a>).</del>
            </p>
          </div>
        </div>

        <div class="Section">
          <h2 class="SubsectionTitle">
            <a class="SectionTitle"
                href="#TOC1.3"
                id="Section1.3"
                name="Section1.3">1.3: Relationship to Other Specifications</a>
          </h2>

          <p class="Copy">
            This specification combines subsets and applications of other specifications. Together,
            these facilitate the construction, organization, presentation, and unambiguous
            interchange of electronic documents:
          </p>

          <ol>
            <li>
              <span class="FormalName">Extensible Markup Language (XML) 1.1 (Second Edition)</span>
              specification (<a href="http://www.w3.org/TR/xml11/"
                  target="_blank"
                  title="The XML 1.1 Specification">http://www.w3.org/TR/xml11/</a>); and
            </li>

            <li>
              <span class="FormalName">Namespaces in XML 1.0 (Second Edition)</span> specification
              (<a href="http://www.w3.org/TR/xml-names11/"
                  target="_blank"
                  title="The XML Namespaces specification.">http://www.w3.org/TR/xml-names11/</a>);
                  and
            </li>

            <li>
              <span class="FormalName">Document Object Model (Core) Level 1</span> (<a href=
              "http://www.w3.org/TR/REC-DOM-Level-1/level-one-core.html"
                  target="_blank"
                  title=
                  "The DOM Level 1 Specification.">http://www.w3.org/TR/REC-DOM-Level-1/level-one-core.html</a>);
                  and
            </li>

            <li>
              <span class="FormalName">XML Pointer Framework</span> (<a href=
              "http://www.w3.org/TR/2003/REC-xptr-framework-20030325/"
                  target="_blank"
                  title=
                  "The XML Pointer Framework specification.">http://www.w3.org/TR/2003/REC-xptr-framework-20030325/</a>);
                  and
            </li>

            <li>
              <span class="FormalName">XHTML™ 1.1 - Module-based XHTML - Second Edition</span>
              specification (<a href="http://www.w3.org/TR/xhtml11/"
                  target="_blank"
                  title="The XHTML 1.1 Specification.">http://www.w3.org/TR/xhtml11/</a>); and
            </li>

            <li>
              <span class="FormalName">Specifications for the Digital Talking Book</span> (DTB)
              (<a href="http://www.niso.org/standards/resources/Z39-86-2005.html"
                  target="_blank"
                  title=
                  "The DTB Specification.">http://www.niso.org/standards/resources/Z39-86-2005.html</a>);
                  and
            </li>

            <li>
              <span class="FormalName">Scalable Vector Graphics (SVG) 1.1 Specification</span>
              (<a href="http://www.w3.org/TR/SVG11/"
                  target="_blank"
                  title="The SVG 1.1 Specification.">http://www.w3.org/TR/SVG11/</a>); and
            </li>

            <li>
              <span class="FormalName">Cascading Style Sheets, level 2</span> specification
              (<a href="http://www.w3.org/TR/REC-CSS2"
                  target="_blank"
                  title="The CSS2 Specification.">http://www.w3.org/TR/REC-CSS2</a>); and
            </li>

            <li>
              <span class="FormalName">Unicode Standard, Version 4.0. Reading, Mass.:
              Addison-Wesley, 2003,</span> as updated from time to time by the publication of new
              versions. (See <a href="http://www.unicode.org/unicode/standard/versions"
                  target="_blank"
                  title=
                  "The latest versions of the Unicode standard.">http://www.unicode.org/unicode/standard/versions</a>
                  for the latest version and additional information on versions of the standard and
                  of the Unicode Character Database).; and
            </li>

            <li>Particular MIME media types (<a href="http://www.ietf.org/rfc/rfc4288.txt"
                  target="_blank"
                  title=
                  "Media Type Specifications and Registration Procedures RFC.">http://www.ietf.org/rfc/rfc4288.txt</a>
                  and <a href="http://www.iana.org/assignments/media-types/index.html"
                  target="_blank"
                  title=
                  "IANA MIME media types document.">http://www.iana.org/assignments/media-types/index.html</a>);
                  and
            </li>

            <li>
              <span class="FormalName">Associating Style Sheets with XML Documents</span> (<a href=
              "http://www.w3.org/TR/xml-stylesheet"
                  target="_blank"
                  title=
                  "Associating Stylesheet with XML Documents note.">http://www.w3.org/TR/xml-stylesheet</a>);
                  and
            </li>

            <li>
              <span class="FormalName">Web Content Accessibility Guidelines 1.0</span> (<a href=
              "http://www.w3.org/TR/WCAG10/"
                  target="_blank"
                  title="WAI Guidelines.">http://www.w3.org/TR/WCAG10/</a>); and
            </li>

            <li>
              <span class="FormalName">RFC 2119: Key words for use in RFCs to Indicate Requirement
              Levels.</span> (<a href="http://www.ietf.org/rfc/rfc2119.txt"
                  target="_blank"
                  title="RFC 2119">http://www.ietf.org/rfc/rfc2119.txt</a>); and
            </li>

            <li>
              <del><span class="FormalName">Synchronized Multimedia Integration Language (SMIL
              2.1)</span> (<a href="http://www.w3.org/TR/2005/REC-SMIL2-20051213/"
                 target="_blank"
                 title=
                 "The SMIL 2.1 specification.">http://www.w3.org/TR/2005/REC-SMIL2-20051213/</a>);
                 and</del>
            </li>

            <li>The OPF specification (<a href="http://www.idpf.org/opf/opf2.0/download/"
                  target="_blank"
                  title="The OPF Specification.">http://www.idpf.org/opf/opf2.0/download/</a>); and
            </li>

            <li>
              <span class="FormalName">Namespace-based Validation Dispatching Language</span>
              (NVDL) (<a href=
              "http://standards.iso.org/ittf/PubliclyAvailableStandards/c038615_ISO_IEC_19757-4_2006(E).zip"
                  target="_blank"
                  title=
                  "Zip file containing the NVDL standard.">http://standards.iso.org/ittf/PubliclyAvailableStandards/c038615_ISO_IEC_19757-4_2006(E).zip</a>)
            </li>
          </ol>

          <div class="Section">
            <h3 class="SubsubsectionTitle">
              <a class="SectionTitle"
                  href="#TOC1.3.1"
                  id="Section1.3.1"
                  name="Section1.3.1">1.3.1: Relationship to XML</a>
            </h3>

            <p class="Copy">
              OPS is based on XML because of its generality and simplicity, and because XML
              documents are likely to adapt well to future technologies and uses. XML also provides
              well-defined rules for the syntax of documents, which decreases the cost to
              implementers and reduces incompatibility across systems. Further, XML is extensible:
              it is not tied to any particular type of document or set of element types, it
              supports internationalization, and it encourages document markup that can represent a
              document’s internal parts more directly, making them amenable to automated formatting
              and other types of computer processing.
            </p>

            <ul>
              <li>Reading Systems <span class="RFC">must</span> be XML processors as defined in XML
              1.1. All OPS Content Documents <span class="RFC">must</span> be valid XML documents
              according to their respective schemas.
              </li>
            </ul>
          </div>

          <div class="Section">
            <h3 class="SubsubsectionTitle">
              <a class="SectionTitle"
                  href="#TOC1.3.2"
                  id="Section1.3.2"
                  name="Section1.3.2">1.3.2: Relationship to XML Namespaces</a>
            </h3>

            <p class="Copy">
              Reading Systems <span class="RFC">must</span> process XML namespaces according to the
              XML Namespaces Recommendation at <a href="http://www.w3.org/TR/xml-names11/"
                 target="_blank"
                 title="The XML Namespaces specification.">http://www.w3.org/TR/xml-names11/</a>.
            </p>

            <p class="Copy">
              Namespace prefixes distinguish identical names that are drawn from different XML
              vocabularies. An XML namespace declaration in an XML document associates a namespace
              prefix with a unique URI. The prefix can then be employed on element or attribute
              names in the document. Alternatively, a namespace declaration in an XML document
              <span class="Emphasis">may</span> identify a URI as the default namespace, applicable
              to elements lacking a namespace prefix. The XML namespace prefix is separated from
              the suffix element or attribute name by a colon.
            </p>

            <p class="Copy">
              Example:
            </p>

            <pre class="Example">
xmlns:ops="http://www.idpf.org/2007/ops"
</pre>
            <p class="Copy">
              The root element of all OPS Content Documents <span class="RFC">must</span>
              explicitly specify the namespace of the document. For the XHTML Preferred Vocabulary,
              this namespace is <span class="Namespace">http://www.w3.org/1999/xhtml</span>. For
              the <del>Daisy</del><ins>DAISY</ins> Talking Book Preferred Vocabulary, this
              namespace is <span class="Namespace">http://www.daisy.org/z3986/2005/dtbook/</span>.
              If the OPS namespace is used in a document it <span class="RFC">must</span> be
              explicitly declared <span class="Namespace">http://www.idpf.org/2007/ops</span>. If a
              namespace prefix is used, it is <span class="RFC">recommended</span> that authors
              bind the <span class="Attribute">ops</span> prefix to that namespace and not use
              <span class="Attribute">ops</span> as the prefix for other namespaces.
            </p>

            <p class="Copy">
              Example:
            </p>

            <pre class="Example">
&lt;html xmlns="http://www.w3.org/1999/xhtml" xmlns:ops=" http://www.idpf.org/2007/ops"&gt;
</pre>
            <p class="Copy">
              As OPS has additional functionality and validation requirements beyond the preferred
              document types and XML islands, there are other namespaces associated with OPS, which
              are used in specific contexts.
            </p>
          </div>

          <div class="Section">
            <h3 class="SubsubsectionTitle">
              <a class="SectionTitle"
                  href="#TOC1.3.3"
                  id="Section1.3.3"
                  name="Section1.3.3">1.3.3: Relationship to NVDL</a>
            </h3>

            <p class="Copy">
              This specification uses the NVDL language (see <a href=
              "http://standards.iso.org/ittf/PubliclyAvailableStandards/c038615_ISO_IEC_19757-4_2006(E).zip"
                 target="_blank"
                 title=
                 "Zip file containing the NVDL Standard.">http://standards.iso.org/ittf/PubliclyAvailableStandards/c038615_ISO_IEC_19757-4_2006(E).zip</a>)
                 as a means to unambiguously define the interaction between the various schemas
                 used in this specification. NVDL allows for interaction and validation between
                 various XML schema languages. See <a href="#AppendixA"
                 title="The NVDL Definition of OPS">Appendix A</a> for a normative NVDL definition
                 of OPS.
            </p>

            <p class="Copy">
              This specification <span class="Emphasis">does not</span> require the use of NVDL
              tools to validate OPS documents, although such tools are available and <span class=
              "RFC">may</span> be used for validation.
            </p>
          </div>

          <div class="Section">
            <h3 class="SubsubsectionTitle">
              <a class="SectionTitle"
                  href="#TOC1.3.4"
                  id="Section1.3.4"
                  name="Section1.3.4">1.3.4: Relationship to XHTML and DTBook</a>
            </h3>

            <p class="Copy">
              This specification recognizes the importance of current software tools, legacy data,
              publication practices, and market conditions, and has therefore incorporated certain
              XHTML 1.1 Document Type Modules and DTBook as Preferred Vocabularies. This approach
              allows content providers to exploit current XHTML and DTBook content, tools, and
              expertise.
            </p>

            <p class="Copy">
              To minimize the implementation burden on Reading System implementers (who may be
              working with devices that have power and display constraints), the Preferred
              Vocabularies do not include all XHTML 1.1 elements and attributes. Further, the
              modules selected from the XHTML 1.1 specification were chosen to be consistent with
              current directions in XHTML.
            </p>

            <p class="Copy">
              Any construct deprecated in XHTML 1.1 is either deprecated or omitted from this
              specification; CSS-based equivalents are provided in most such cases. Style sheet
              constructs are also used for new presentational functionality beyond that provided in
              XHTML.
            </p>
          </div>

          <div class="Section">
            <h3 class="SubsubsectionTitle">
              <a class="SectionTitle"
                  href="#TOC1.3.5"
                  id="Section1.3.5"
                  name="Section1.3.5">1.3.5: Relationship to CSS</a>
            </h3>

            <p class="Copy">
              This specification defines a style language based on CSS 2. (Note that the CSS 2.1
              specification is currently still at "Working Draft" status.) The style sheet MIME
              type <span class="MIMEType">text/x-oeb1-css</span> has been deprecated in favor of
              <span class="MIMEType">text/css</span>.
            </p>

            <p class="Copy">
              The CSS-based style sheet constructs in this specification define required rendering
              functionality. To minimize the burden on Reading System developers and device
              manufacturers, not all CSS 2 properties are included. A few additional properties and
              values have been added to support page layout, headers, and footers. These, taken
              together, constitute the OPS CSS 2.0 required subset.
            </p>

            <p class="Copy">
              In a number of cases, this specification does not require Reading Systems to provide
              the full range of rendering that a standard CSS style sheet might request. For
              example, some Reading Systems will use monochrome displays. It would neither be
              acceptable to limit all Reading Systems to monochrome, nor to declare color use a
              non-standardized extension beyond OPS. In such cases, the CSS settings are allowed,
              and keep their meanings; but a conforming Reading System <span class="RFC">may</span>
              gracefully degrade to a simpler rendering.
            </p>

            <p class="Copy">
              A conforming Reading System <span class="RFC">must</span> render all OPS CSS 2.0
              <a href="#Section3.0"
                 title="OPS Style Sheets">required subset properties</a>. A Reading System
                 <span class="RFC">may</span> support CSS properties beyond the OPS CSS 2.0
                 required subset, however, any unsupported properties <span class="RFC">must</span>
                 be gracefully degraded per the CSS 2.0 specification.
            </p>

            <p class="Copy">
              This specification supports the <span class="Attribute">style</span> attribute
              (though deprecated), the <span class="Element">style</span> element, and externally
              linked style sheets. Reading Systems <span class="RFC">must</span> perform
              XML-namespace handling while processing style sheets.
            </p>

            <p class="Copy">
              Style sheets can be associated with an OPS Content Document in several ways:
            </p>

            <ul>
              <li>by <span class="Attribute">style</span> attributes on specific XHTML elements
              (deprecated); and
              </li>

              <li>by <span class="Element">style</span> elements within the XHTML <span class=
              "Element">head</span> element; and
              </li>

              <li>by an external style sheet identified on <span class="Element">link</span>
              elements in the XHTML <span class="Element">head</span> element; and
              </li>

              <li>by an external style sheet identified via the processing instruction
                <span class="Element">xml-stylesheet</span> (see <a href="#Section1.3.8"
                    title="XML Style Sheet Processing Instruction">Section 1.3.8</a>).
              </li>
            </ul>

            <p class="Copy">
              The relative priority of the first three cases is as defined for XHTML 1.1 and CSS 2.
              Style sheets linked via a processing instruction are treated as if they had been
              linked via XHTML <span class="Element">link</span> elements preceding any actual
              XHTML <span class="Element">link</span> elements. As defined in the Conformance
              section, if no style sheet is defined or no applicable style is found for a given
              element, XHTML rendering is the default as defined elsewhere in this specification.
            </p>

            <p class="Copy">
              External style sheets linked via the XHTML <span class="Element">link</span> element
              or by the processing instruction <span class="Element">xml-stylesheet</span><del>,
              however,</del> <span class="RFC">may</span> use <del>this</del><ins>CSS</ins> or any
              other style language, such as XSL (see <a href="http://www.w3.org/TR/xsl"
                 target="_blank"
                 title="The XSL specification.">http://www.w3.org/TR/xsl</a>). Reading Systems are
                 not required to support any style sheet language beyond the CSS specified herein.
            </p>

            <p class="Copy">
              Reading Systems that implement only the OPS CSS 2.0 required subset <span class=
              "RFC">may</span> ignore any style sheets using other style languages. Reading Systems
              that support extended style sheet functionality <span class="RFC">may</span> choose
              among any of the other external style sheets. It is <span class="RFC">strongly
              recommended</span> that unique MIME media types be defined for any style sheet
              languages supported beyond the OPS CSS 2.0 required subset, and that style sheets in
              those languages be detected by examining the MIME media type.
            </p>

            <p class="Copy">
              Use of the CSS position property values to achieve absolute positioning (i.e.
              <span class="CSSPropertyValue">absolute</span> and <span class=
              "CSSPropertyValue">fixed</span>) is strongly discouraged.
            </p>
          </div>

          <div class="Section">
            <h3 class="SubsubsectionTitle">
              <a class="SectionTitle"
                  href="#TOC1.3.6"
                  id="Section1.3.6"
                  name="Section1.3.6">1.3.6: Relationship to Unicode</a>
            </h3>

            <p class="Copy">
              Publications <span class="RFC">may</span> use the entire Unicode character set, using
              UTF-8 or UTF-16 encodings, as defined by Unicode (see <a href=
              "http://www.unicode.org/unicode/standard/versions"
                 target="_blank"
                 title=
                 "The Unicode Standard">http://www.unicode.org/unicode/standard/versions</a>). The
                 use of Unicode facilitates internationalization and multilingual documents.
                 However, Reading Systems are <span class="RFC">not required</span> to provide
                 glyphs for all Unicode characters.
            </p>

            <p class="Copy">
              Reading Systems <span class="RFC">must</span> parse all UTF-8 and UTF-16 characters
              properly (as required by XML). Reading Systems <span class="RFC">may</span> decline
              to display some characters, but <span class="RFC">must</span> be capable of signaling
              in some fashion that undisplayable characters are present. Reading Systems
              <span class="RFC">must not</span> display Unicode characters merely as if they were
              8-bit characters. For example, the biohazard symbol (0x2623) need not be supported by
              including the correct glyph, but <span class="RFC">must not</span> be parsed or
              displayed as if its component bytes were the two characters "&amp;#" (0x0026 0x0023).
            </p>

            <p class="Copy">
              To aid Reading Systems in implementing consistent searching and sorting behavior it
              is <span class="RFC">required</span> that Unicode Normalization Form C (NFC) be used
              (See <a href="http://www.w3.org/TR/charmod-norm/"
                 target="_blank"
                 title="Unicode Normalization Form C">http://www.w3.org/TR/charmod-norm/</a>).
            </p>
          </div>

          <div class="Section">
            <h3 class="SubsubsectionTitle">
              <a class="SectionTitle"
                  href="#TOC1.3.7"
                  id="Section1.3.7"
                  name="Section1.3.7">1.3.7: MIME Media Types</a>
            </h3>

            <p class="Copy">
              This specification defines a list of OPS Core Media Types that all Reading Systems
              <span class="RFC">must</span> support and publications <span class="RFC">may</span>
              include. Publications <span class="RFC">may</span> include resources of other media
              types, but each such resource <span class="RFC">must</span> include an alternative
              resource of an OPS Core Media Type using methods defined in this specification or the
              <a href="http://www.idpf.org/opf/opf2.0/download/"
                 target="_blank"
                 title="The OPF Specification">OPF specification</a>.
            </p>

            <p class="Copy">
              The OPS Core Media Types are:
            </p>

            <table summary="OPS Core Media types">
              <thead>
                <tr>
                  <td>
                    MIME Media Type
                  </td>
                  <td>
                    Reference
                  </td>
                  <td>
                    Description
                  </td>
                </tr>
              </thead>

              <tbody>
                <tr>
                  <td>
                    <span class="Element">image/gif</span>
                  </td>
                  <td>
                    <a href="http://www.w3.org/Graphics/GIF/spec-gif89a.txt"
                        target="_blank"
                        title=
                        "The GIF specification.">http://www.w3.org/Graphics/GIF/spec-gif89a.txt</a>
                  </td>
                  <td>
                    Used for raster graphics
                  </td>
                </tr>

                <tr>
                  <td>
                    <span class="Element">image/jpeg</span>
                  </td>
                  <td>
                    <a href="http://www.w3.org/Graphics/JPEG/"
                        target="_blank"
                        title="JPEG Information Page.">http://www.w3.org/Graphics/JPEG/</a>
                  </td>
                  <td>
                    Used for raster graphics
                  </td>
                </tr>

                <tr>
                  <td>
                    <span class="Element">image/png</span>
                  </td>
                  <td>
                    <a href="http://www.ietf.org/rfc/rfc2083.txt"
                        target="_blank"
                        title="PNG Specification.">RFC 2083</a>
                  </td>
                  <td>
                    Used for raster graphics
                  </td>
                </tr>

                <tr>
                  <td>
                    <span class="Element">image/svg+xml</span>
                  </td>
                  <td>
                    <a href="http://www.w3.org/TR/SVG11/"
                        target="_blank"
                        title="SVG specification.">http://www.w3.org/TR/SVG11/</a>
                  </td>
                  <td>
                    Used for <del>raster</del><ins>vector</ins> graphics
                  </td>
                </tr>

                <tr>
                  <td>
                    <span class="Element">application/xhtml+xml</span>
                  </td>
                  <td>
                    <a href="http://www.w3.org/TR/xhtml11/"
                        target="_blank"
                        title="XHTML 1.1 specification.">XHTML 1.1</a>
                  </td>
                  <td>
                    Used for OPS Content Documents
                  </td>
                </tr>

                <tr>
                  <td>
                    <span class="Element">application/x-dtbook+xml</span>
                  </td>
                  <td>
                    <a href="http://www.niso.org/standards/resources/Z39-86-2005.html"
                        target="_blank"
                        title=
                        "The DTBook specification.">http://www.niso.org/standards/resources/Z39-86-2005.html</a>
                  </td>
                  <td>
                    Used for OPS Content Documents
                  </td>
                </tr>

                <tr>
                  <td>
                    <span class="Element">text/css</span>
                  </td>
                  <td>
                    <a href="http://www.w3.org/TR/REC-CSS2/"
                        target="_blank"
                        title="CSS2 specification.">CSS 2.0</a>
                  </td>
                  <td>
                    Used for OPS CSS-subset style sheets
                  </td>
                </tr>

                <tr>
                  <td>
                    <span class="Element">application/xml</span>
                  </td>
                  <td>
                    <a href="http://www.w3.org/TR/xml11/"
                        target="_blank"
                        title="The XML Specification.">http://www.w3.org/TR/xml11/</a>
                  </td>
                  <td>
                    Used for Out-Of-Line XML Islands
                  </td>
                </tr>

                <tr>
                  <td>
                    <span class="Element">text/x-oeb1-document</span>
                  </td>
                  <td>
                    <a href="http://www.idpf.org/oebps/oebps1.2/download/oeb12-xhtml.htm"
                        target="_blank"
                        title="OEBPS 1.2 specification.">OEBPS 1.2 specification</a>
                  </td>
                  <td>
                    Deprecated; Used for Basic or Extended OEBPS 1.0.1 and 1.2 Documents
                  </td>
                </tr>

                <tr>
                  <td>
                    <span class="Element">text/x-oeb1-css</span>
                  </td>
                  <td>
                    <a href="http://www.idpf.org/oebps/oebps1.2/download/oeb12-xhtml.htm"
                        target="_blank"
                        title="OEBPS 1.2 specification.">OEBPS 1.2 specification</a>
                  </td>
                  <td>
                    Deprecated; Used for OEBPS 1.0.1 and 1.2 CSS-subset style sheets
                  </td>
                </tr>

                <tr>
                  <td>
                    <ins><span class="Element">application/x-dtbncx+xml</span></ins>
                  </td>
                  <td>
                    <ins><a href="http://www.niso.org/standards/resources/Z39-86-2005.html"
                       target="_blank"
                       title="DTBook specification.">DTBook specification</a></ins>
                  </td>
                  <td>
                    <ins>The NCX</ins>
                  </td>
                </tr>
              </tbody>
            </table>
          </div>

          <div class="Section">
            <h3 class="SubsubsectionTitle">
              <a class="SectionTitle"
                  href="#TOC1.3.8"
                  id="Section1.3.8"
                  name="Section1.3.8">1.3.8: XML Style Sheet Processing Instruction</a>
            </h3>

            <p class="Copy">
              This specification includes support for the XML style sheet processing instruction
              <span class="Element">xml-stylesheet</span>, defined in the W3C Recommendation
              "Associating Style Sheets with XML Documents" (<a href=
              "http://www.w3.org/TR/xml-stylesheet"
                 target="_blank"
                 title=
                 "Associating Style Sheets with XML Documents specification.">http://www.w3.org/TR/xml-stylesheet</a>).
                 This processing instruction is placed in the prolog of the XML document. It can
                 appear multiple times as can <span class="Element">link</span>.
            </p>
          </div>
        </div>

        <div class="Section">
          <h2 class="SubsectionTitle">
            <a class="SectionTitle"
                href="#TOC1.4"
                id="Section1.4"
                name="Section1.4">1.4: Conformance</a>
          </h2>

          <p class="Copy">
            The keywords "<span class="RFC">must</span>", "<span class="RFC">must not</span>",
            "<span class="RFC">required</span>", "<span class="RFC">shall</span>", "<span class=
            "RFC">shall not</span>", "<span class="RFC">should</span>", "<span class=
            "RFC">recommended</span>", "<span class="RFC">may</span>", and "<span class=
            "RFC">optional</span>" in this document <span class="RFC">must</span> be interpreted as
            described in <a href="http://www.ietf.org/rfc/rfc2119.txt"
               target="_blank"
               title="RFC 2119.">RFC 2119</a>.
          </p>

          <p class="Copy">
            This section defines conformance for OPS Content Documents and Reading Systems.
          </p>

          <div class="Section">
            <h3 class="SubsubsectionTitle">
              <a class="SectionTitle"
                  href="#TOC1.4.1"
                  id="Section1.4.1"
                  name="Section1.4.1">1.4.1: OPS Content Document Conformance</a>
            </h3>

            <p class="Copy">
              This section defines conformance for OPS Content Documents.
            </p>

            <div class="Section">
              <h4 class="SubsubsubsectionTitle">
                <a class="SectionTitle"
                    href="#TOC1.4.1.1"
                    id="Section1.4.1.1"
                    name="Section1.4.1.1">1.4.1.1: OPS Content Document</a>
              </h4>

              <p class="Copy">
                A document is considered an OPS Content Document if and only if:
              </p>

              <ol class="BulletStyle_lower-roman">
                <li>it uses a combination of the XHTML subset defined in this document and
                OPS-specific content extensions such as Inline XML Islands and Inline SVG; or
                </li>

                <li>it is a document with the MIME media type <span class=
                "MIMEType">application/x-dtbook+xml</span> which conforms to the DTB specification
                (<a href="http://www.niso.org/standards/resources/Z39-86-2005.html"
                      target="_blank"
                      title=
                      "The DTBook specification.">http://www.niso.org/standards/resources/Z39-86-2005.html</a>)
                      and <span class="RFC">must not</span> use OPS-specific content extensions
                      such as Inline XML Islands or Inline SVG; or
                </li>

                <li>it is an XML document of any other MIME media type and is thus an Out-Of-Line
                XML Island
                </li>
              </ol>
            </div>

            <div class="Section">
              <h4 class="SubsubsubsectionTitle">
                <a class="SectionTitle"
                    href="#TOC1.4.1.2"
                    id="Section1.4.1.2"
                    name="Section1.4.1.2">1.4.1.2: XHTML <ins>Content</ins> Document
                    Requirements</a>
              </h4>

              <p class="Copy">
                A conformant XHTML Content Document <span class="RFC">must</span> meet these
                conditions:
              </p>

              <ol class="BulletStyle_lower-roman">
                <li>it is a well-formed XML document (as defined by XML 1.1); and
                </li>

                <li>it is encoded in UTF-8 or UTF-16; and
                </li>

                <li>it is a valid XML document according to the NVDL schema interaction provided in
                <a href="#AppendixA"
                      target="_blank"
                      title="NVDL Schema for OPS.">Appendix A</a>; and
                </li>

                <li>it has a MIME media type of either <span class=
                "MIMEType">application/xhtml+xml</span> or <span class=
                "MIMEType">text/x-oeb1-document</span> (deprecated); and
                </li>

                <li>all XHTML elements and attributes not contained in an Inline XML Island are
                drawn from the XHTML subset identified in this document.
                </li>
              </ol>
            </div>

            <div class="Section">
              <h4 class="SubsubsubsectionTitle">
                <a class="SectionTitle"
                    href="#TOC1.4.1.3"
                    id="Section1.4.1.3"
                    name="Section1.4.1.3">1.4.1.3: DTBook Content Document Requirements</a>
              </h4>

              <p class="Copy">
                A document is a DTBook Content Document if and only if:
              </p>

              <ol class="BulletStyle_lower-roman">
                <li>it is a well-formed XML document (as defined by XML 1.1); and
                </li>

                <li>it is encoded in UTF-8 or UTF-16; and
                </li>

                <li>it is a valid XML document, according to the DTBook DTD (<a href=
                "http://www.daisy.org/z3986/2005/dtbook-2005-2.dtd"
                      target="_blank"
                      title=
                      "The DTBook DTD.">http://www.daisy.org/z3986/2005/dtbook-2005-2.dtd</a>); and
                </li>

                <li>it has a MIME media type of <span class=
                "MIMEType">application/x-dtbook+xml</span>.
                </li>
              </ol>
            </div>

            <div class="Section">
              <h4 class="SubsubsubsectionTitle">
                <a class="SectionTitle"
                    href="#TOC1.4.1.4"
                    id="Section1.4.1.4"
                    name="Section1.4.1.4">1.4.1.4: Out-of-Line XML Island Content Document
                    Requirements</a>
              </h4>

              <p class="Copy">
                A document is an Out-of-line XML Island Content Document if and only if:
              </p>

              <ol class="BulletStyle_lower-roman">
                <li>it is a well-formed and valid XML document (<del>as defined by XML
                1.1</del><ins>according to its schema</ins>); and
                </li>

                <li>it is encoded in UTF-8 or UTF-16; and
                </li>

                <li>it has a MIME media type other than <span class=
                "MIMEType">application/xhtml+xml</span>, <span class=
                "MIMEType">text/x-oeb1-document</span> or <span class=
                "MIMEType">application/x-dtbook+xml</span>.
                </li>
              </ol>
            </div>
          </div>

          <div class="Section">
            <h3 class="SubsubsectionTitle">
              <a class="SectionTitle"
                  href="#TOC1.4.2"
                  id="Section1.4.2"
                  name="Section1.4.2">1.4.2: Reading System Conformance</a>
            </h3>

            <p class="Copy">
              This specification defines only one level of conformance for a Reading System. A
              Reading System is conformant if and only if it processes documents as follows:
            </p>

            <p class="Copy">
              When presented with an OPS Content Document the Reading System <span class=
              "RFC">must</span>:
            </p>

            <ol class="BulletStyle_lower-roman">
              <li>correctly process the XML as required in the XML 1.1 specification, including
              that specification’s requirements for the handling of well-formedness errors; and
              </li>

              <li>recognize all markup described as permitted in this specification and processes
              it consistently with the corresponding explanations in this specification and in
              those of XHTML 1.1, CSS 2, and DTBook (in case of any conflict, this specification
              takes precedence); and
              </li>

              <li>not render <span class="Element">img</span> or <span class=
              "Element">object</span> elements of unsupported media types, in the absence of
              fallbacks. These fallbacks are clearly defined herein — <span class=
              "Element">img</span> in <a href="#Section2.3.4"
                    title="img Element">Section 2.3.4</a> and <span class="Element">object</span>
                    in <a href="#Section2.3.6"
                    title="object Element">Section 2.3.6</a>; and
              </li>

              <li>verify the existence of the appropriate namespace specifications, as defined in
              the <a href="#Section1.3.2"
                    title="Section 1.3.2">Relationship to XML Namespaces</a> section above.
              </li>
            </ol>
          </div>

          <div class="Section">
            <h3 class="SubsubsectionTitle">
              <a class="SectionTitle"
                  href="#TOC1.4.3"
                  id="Section1.4.3"
                  name="Section1.4.3">1.4.3: Compatibility with Future Versions</a>
            </h3>

            <p class="Copy">
              It is the intent of the contributors to this specification that subsequent
              generations of this specification continue in currently established directions.
              Specifically:
            </p>

            <ul>
              <li>Content format standards will be compatible with W3C, IETF and other applicable
              standards; and
              </li>

              <li>Future versions of this specification are expected to continue to improve
              alignment with XML-based specifications, requiring further XML processing capability
              of OPS-conformant Reading Systems, and enabling support for other applicable
              XML-related standards; and
              </li>

              <li>Future versions of this specification are expected to improve the richness of
              hyperlinking in OPS documents; and
              </li>

              <li>Any required functionality not present in relevant official standards shall be
              defined in a manner consistent with its eventual submission to an appropriate
              standards body as extensions to existing standards; and
              </li>

              <li>Continued alignment with the affiliated OPF specification; and
              </li>

              <li>Continued alignment and integration with the OCF content packaging standard.
              </li>
            </ul>
          </div>

          <div class="Section">
            <h3 class="SubsubsectionTitle">
              <a class="SectionTitle"
                  href="#TOC1.4.4"
                  id="Section1.4.4"
                  name="Section1.4.4">1.4.4: Compatibility of OPS Version 2.0</a>
            </h3>

            <p class="Copy">
              Version 2.0 of OPS offers fairly significant enhancements over its preceding version,
              OEBPS 1.2. Version 2.0 adds substantial functional enhancements over 1.2, these
              include: supporting enhanced control over content presentational fidelity, providing
              an enhanced extension mechanism, improving accessibility, and improving alignment
              with the standards upon which OPS is based. Specifically, the following are the most
              substantive additions:
            </p>

            <ul>
              <li>XML 1.1 is incorporated, and the bar has been raised from XML "well-formedness"
              to XML validity.
              </li>

              <li>XML namespace processing is now required.
              </li>

              <li>The concept of Basic and Extended documents has been removed and replaced with
              two XML Preferred Vocabularies and a new XML island-based extension mechanism.
              </li>

              <li>The OPS subset of the XHTML element set has been replaced with reference to
              specific modules within XHTML 1.1.
              </li>

              <li>The DTBook element set is now a Preferred Vocabulary.
              </li>

              <li>Support for SVG has been added.
              </li>

              <li>Support for embedded fonts has been added.
              </li>

              <li>The OEBPS 1.2 Package has been extended for enhanced navigation and accessibility
              and the documentation thereof has been moved into the now separate OPF specification.
              </li>

              <li>Older OEBPS-specific MIME types have been deprecated and replaced with more
              widely used standard MIME types.
              </li>
            </ul>

            <p class="Copy">
              While most changes from version OEBPS 1.2 to OPS 2.0 have been done via deprecation
              rather than removal of previous functionality, OEBPS version 1.2 is not a fully
              compatible subset of OPS 2.0 (e.g. new XML validity and namespace processing
              requirements).
            </p>
          </div>
        </div>

        <div class="Section">
          <h2 class="SubsectionTitle">
            <a class="SectionTitle"
                href="#TOC1.5"
                id="Section1.5"
                name="Section1.5">1.5: Extensibility</a>
          </h2>

          <p class="Copy">
            XML Islands are the <span class="RFC">recommended</span> mechanism for adding
            functionality, information or structure beyond that supported by the Preferred
            Vocabularies.
          </p>

          <p class="Copy">
            Out-Of-Line XML Islands <span class="RFC">may</span> be used in any publication. Inline
            XML Islands <del><span class="RFC">may</span></del><ins><span class="RFC">must
            not</span></ins> <del>only</del> be used within documents authored using <ins>other
            than</ins> the XHTML Preferred Vocabulary.
          </p>
        </div>

        <div class="Section">
          <h2 class="SubsectionTitle">
            <a class="SectionTitle"
                href="#TOC1.6"
                id="Section1.6"
                name="Section1.6">1.6: Accessibility</a>
          </h2>

          <p class="Copy">
            This specification incorporates features that ensure content can be made accessible to,
            and usable by, persons with reading disabilities. Existing accessibility features
            developed by the World Wide Web Consortium (W3C) for XHTML 1.1 for content
            accessibility are incorporated into this specification.
          </p>

          <p class="Copy">
            OPS <ins>XHTML Content Documents</ins><del>Publications</del> <span class=
            "RFC">should</span> be authored in accordance with the W3C Web Content Accessibility
            Guidelines 1.0 (<a href="http://www.w3.org/TR/1999/WAI-WEBCONTENT-19990505/"
               target="_blank"
               title=
               "WAI 1.0 specification.">http://www.w3.org/TR/1999/WAI-WEBCONTENT-19990505/</a>) or,
               if it is released while the Working Group is active, the Web Content Accessibility
               Guidelines 2.0 (the current draft is available at <a href=
               "http://www.w3.org/TR/WCAG20/"
               target="_blank"
               title="WAI 2.0 specification.">http://www.w3.org/TR/WCAG20/</a> to ensure that the
               broadest possible set of users will have access to books delivered in OPS format.
          </p>

          <p class="Copy">
            In addition, recommendations from the W3C HTML 4.0 Guidelines for Mobile Access
            (<a href="http://www.w3.org/TR/NOTE-html40-mobile/"
               target="_blank"
               title=
               "Guidelines for Mobile Access specification.">http://www.w3.org/TR/NOTE-html40-mobile/</a>)
               and the W3C Web Accessibility Initiative's proposed User Agent Guidelines (<a href=
               "http://www.w3.org/TR/WD-WAI-USERAGENT/"
               target="_blank"
               title=
               "WAI User Agent Guidelines specification.">http://www.w3.org/TR/WD-WAI-USERAGENT/</a>)
               ought to be reviewed and applied by OPS implementers to ensure that Reading Systems
               will be in conformance with accessibility requirements.
          </p>
        </div>

        <div class="Section">
          <h2 class="SubsectionTitle">
            <a class="SectionTitle"
                href="#TOC1.7"
                id="Section1.7"
                name="Section1.7">1.7: Future Directions</a>
          </h2>

          <p class="Copy">
            This specification is designed to take advantage of current practices while preparing
            for future developments. Although details of subsequent versions of this specification
            remain to be determined, it is the expectation of the Publication Structure Working
            Group that continued evolutionary development will occur. The themes driving the
            creation of version 2.0 of OPS are: standards compliance (e.g. full namespace support),
            accessibility support, <del>support for any XML document type</del><ins>support for a
            wide-range of XML document vocabularies</ins>, enhanced navigation support, and
            improved content presentational fidelity.
          </p>

          <p class="Copy">
            Other themes deemed important for future versions include: more rigorous separation of
            content and presentation, greater accessibility, better support for international
            content, Reading Device-specific presentation control and/or Reading Device profiles,
            enhanced support for inter-Publication linking, layering and managing markups (e.g.
            inking, highlighting, notes) within Publications, application-specific markup (e.g.
            math, chemical), multiple reading orders, and support for active content (e.g.
            multimedia, scripting), all while maintaining alignment with relevant standards.
            Additionally, maintaining backward compatibility to this version of this specification
            ought to remain a high priority. Future directions can be tracked at <a href=
            "http://www.idpf.org"
               target="_blank"
               title="IDPF website.">http://www.idpf.org</a>.
          </p>
        </div>
      </div>

      <div class="Section">
        <h1 class="SectionTitle">
          <a class="SectionTitle"
              href="#TOC2.0"
              id="Section2.0"
              name="Section2.0">2.0: OPS Content Document Vocabularies</a>
        </h1>

        <div class="Section">
          <h2 class="SubsectionTitle">
            <a class="SectionTitle"
                href="#TOC2.1"
                id="Section2.1"
                name="Section2.1">2.1: Introduction</a>
          </h2>

          <p class="Copy">
            OEBPS 1.2 and its predecessors specified a "Basic" document vocabulary, drawn from the
            XHTML 1.1 document type, which all Reading Systems were required to support. This
            specification no longer creates its own subset of XHTML 1.1, but instead references
            entire XHTML modules, as described in XHTML Modularization 1.1 (<a href=
            "http://www.w3.org/TR/xhtml-modularization/"
               target="_blank"
               title=
               "XHTML Modularization specification.">http://www.w3.org/TR/xhtml-modularization/</a>).
               In addition to XHTML, OPS adds the DAISY DTBook document type as a Preferred
               Vocabulary (see <a href="http://www.niso.org/standards/resources/Z39-86-2005.html"
               target="_blank"
               title=
               "DTBook specification.">http://www.niso.org/standards/resources/Z39-86-2005.html</a>).
          </p>

          <p class="Copy">
            The XHTML modules listed in this section and the DTBook vocabulary are considered the
            OPS Preferred Vocabularies. The concepts of "Basic" and "Extended" documents are no
            longer used by this specification. OPS publications <span class="RFC">should</span> use
            one of the Preferred Vocabularies. Publications that use other vocabularies, either as
            entire documents or as XML fragments, <span class="RFC">must</span> use the Inline or
            Out-Of-Line XML Island mechanisms, described elsewhere in this specification. XHTML
            modules beyond those listed here (Extended Modules) <span class="RFC">may</span> be
            used in a conforming publication, but <span class="RFC">must</span> follow the
            guidelines set forth in the <a href="#Section2.6"
               title="Section 2.6">XML Islands</a> section of this document.
          </p>

          <p class="Copy">
            <ins>As with any DTD referenced from the DOCTYPE declaration, OPS XHTML Content
            Documents <span class="RFC">must not</span> reference the XHTML DTD unless such
            documents are valid with respect to that DTD (i.e. it do not include Inline XML Islands
            or inline SVG).</ins>
          </p>
        </div>

        <div class="Section">
          <h2 class="SubsectionTitle">
            <a class="SectionTitle"
                href="#TOC2.2"
                id="Section2.2"
                name="Section2.2">2.2: XHTML Modules in the OPS Preferred Vocabulary</a>
          </h2>

          <div class="Section">
            <h3 class="SubsubsectionTitle">
              <a class="SectionTitle"
                  href="#TOC2.2.1"
                  id="Section2.2.1"
                  name="Section2.2.1">2.2.1: Required Modules</a>
            </h3>

            <p class="Copy">
              OPS requires all conforming Reading Systems to support the following modules
              consistent with their descriptions in the <a href="http://www.w3.org/TR/xhtml11/"
                 target="_blank"
                 title="XHTML 1.1 specification.">XHTML</a> and <a href=
                 "http://www.w3.org/TR/html4/"
                 target="_blank"
                 title="HTML 4.01 specification.">HTML</a> specifications, unless otherwise
                 specified in this document.
            </p>

            <table summary="OPS XHTML required Modules">
              <thead>
                <tr>
                  <td>
                    XHTML 1.1 Module Name
                  </td>
                  <td>
                    Elements (non-normative)
                  </td>
                </tr>
              </thead>

              <tbody>
                <tr>
                  <td>
                    Structure
                  </td>
                  <td>
                    <span class="Element">body</span>, <span class="Element">head</span>,
                    <span class="Element">html</span>, <span class="Element">title</span>
                  </td>
                </tr>

                <tr>
                  <td>
                    Text
                  </td>
                  <td>
                    <span class="Element">abbr</span>, <span class="Element">acronym</span>,
                    <span class="Element">address</span>, <span class="Element">blockquote</span>,
                    <span class="Element">br</span>, <span class="Element">cite</span>,
                    <span class="Element">code</span>, <span class="Element">dfn</span>,
                    <span class="Element">div</span>, <span class="Element">em</span>, <span class=
                    "Element">h1</span>, <span class="Element">h2</span>, <span class=
                    "Element">h3</span>, <span class="Element">h4</span>, <span class=
                    "Element">h5</span>, <span class="Element">h6</span>, <span class=
                    "Element">kbd</span>, <span class="Element">p</span>, <span class=
                    "Element">pre</span>, <span class="Element">q</span>, <span class=
                    "Element">samp</span>, <span class="Element">span</span>, <span class=
                    "Element">strong</span>, <span class="Element">var</span>
                  </td>
                </tr>

                <tr>
                  <td>
                    Hypertext
                  </td>
                  <td>
                    <span class="Element">a</span>
                  </td>
                </tr>

                <tr>
                  <td>
                    List
                  </td>
                  <td>
                    <span class="Element">dl</span>, <span class="Element">dt</span>, <span class=
                    "Element">dd</span>, <span class="Element">ol</span>, <span class=
                    "Element">ul</span>, <span class="Element">li</span>
                  </td>
                </tr>

                <tr>
                  <td>
                    Object
                  </td>
                  <td>
                    <span class="Element">object</span>, <span class="Element">param</span>
                  </td>
                </tr>

                <tr>
                  <td>
                    Presentation
                  </td>
                  <td>
                    <span class="Element">b</span>, <span class="Element">big</span>, <span class=
                    "Element">hr</span>, <span class="Element">i</span>, <span class=
                    "Element">small</span>, <span class="Element">sub</span>, <span class=
                    "Element">sup</span>, <span class="Element">tt</span>
                  </td>
                </tr>

                <tr>
                  <td>
                    Edit
                  </td>
                  <td>
                    <span class="Element">del</span>, <span class="Element">ins</span>
                  </td>
                </tr>

                <tr>
                  <td>
                    Bidirectional Text
                  </td>
                  <td>
                    <span class="Element">bdo</span>
                  </td>
                </tr>

                <tr>
                  <td>
                    Table
                  </td>
                  <td>
                    <span class="Element">caption</span>, <span class="Element">col</span>,
                    <span class="Element">colgroup</span>, <span class="Element">table</span>,
                    <span class="Element">tbody</span>, <span class="Element">td</span>,
                    <span class="Element">tfoot</span>, <span class="Element">th</span>,
                    <span class="Element">thead</span>, <span class="Element">tr</span>
                  </td>
                </tr>

                <tr>
                  <td>
                    Image
                  </td>
                  <td>
                    <span class="Element">img</span>
                  </td>
                </tr>

                <tr>
                  <td>
                    Client-Side Image Map
                  </td>
                  <td>
                    <span class="Element">area</span>, <span class="Element">map</span>
                  </td>
                </tr>

                <tr>
                  <td>
                    Meta-Information
                  </td>
                  <td>
                    <span class="Element">meta</span>
                  </td>
                </tr>

                <tr>
                  <td>
                    Style Sheet
                  </td>
                  <td>
                    <span class="Element">style</span>
                  </td>
                </tr>

                <tr>
                  <td>
                    Style Attribute (deprecated)
                  </td>
                  <td>
                    <span class="Attribute">style</span> attribute
                  </td>
                </tr>

                <tr>
                  <td>
                    Link
                  </td>
                  <td>
                    <span class="Element">link</span>
                  </td>
                </tr>

                <tr>
                  <td>
                    Base
                  </td>
                  <td>
                    <span class="Element">base</span>
                  </td>
                </tr>
              </tbody>
            </table>
          </div>
        </div>

        <div class="Section">
          <h2 class="SubsectionTitle">
            <a class="SectionTitle"
                href="#TOC2.3"
                id="Section2.3"
                name="Section2.3">2.3: Certain Element and Attribute Semantic Differences From, and
                Restrictions Beyond, XHTML 1.1</a>
          </h2>

          <p class="Copy">
            As previously noted, the semantics and rendering behavior of the XHTML Preferred
            Vocabulary (elements, attributes, and associated attribute values) strictly follows
            that of XHTML 1.1. However, there are several restrictions beyond that of XHTML 1.1, as
            noted below. These restrictions have no effect on the XHTML 1.1 conformance of OPS
            documents.
          </p>

          <div class="Section">
            <h3 class="SubsubsectionTitle">
              <a class="SectionTitle"
                  href="#TOC2.3.1"
                  id="Section2.3.1"
                  name="Section2.3.1">2.3.1: General Comments on URI References</a>
            </h3>

            <p class="Copy">
              A number of attributes reference resources using URI values (Uniform Resource
              Identifier, see RFC 2396, <a href="http://www.ietf.org/rfc/rfc2396.txt"
                 target="_blank"
                 title="RFC 2396">http://www.ietf.org/rfc/rfc2396.txt</a>). Depending on the
                 particular attribute, the URI referenced resource can either be an abstract entity
                 or a physical object.
            </p>

            <p class="Copy">
              Except where noted or where not applicable, Reading Systems <span class=
              "RFC">may</span> use or render a URI referenced physical resource not listed in the
              Manifest (i.e., it is not a component of the Publication), but they are <span class=
              "RFC">not required</span> to do so.
            </p>
          </div>

          <div class="Section">
            <h3 class="SubsubsectionTitle">
              <a class="SectionTitle"
                  href="#TOC2.3.2"
                  id="Section2.3.2"
                  name="Section2.3.2">2.3.2: <span class="Element">body</span> Element</a>
            </h3>

            <p class="Copy">
              It is assumed, in formatting, that the default rendering for <span class=
              "Element">body</span> is consistent with the CSS property <span class=
              "CSSProperty">page-break-before</span> having been set to <span class=
              "CSSPropertyValue">right</span> (which behaves like <span class=
              "CSSPropertyValue">always</span> on one-page Reading Systems), but <span class=
              "RFC">may</span> be overridden by an appropriate style sheet declaration.
            </p>
          </div>

          <div class="Section">
            <h3 class="SubsubsectionTitle">
              <a class="SectionTitle"
                  href="#TOC2.3.3"
                  id="Section2.3.3"
                  name="Section2.3.3">2.3.3: <span class="Attribute">cite</span> Attribute</a>
            </h3>

            <p class="Copy">
              The <span class="RFC">optional</span> attribute <span class="Attribute">cite</span>
              <span class="RFC">may</span> be used in <span class="Element">blockquote</span>,
              <span class="Element">q</span>, <span class="Element">del</span> and <span class=
              "Element">ins</span> to provide a URI citation for the element contents. Reading
              Systems are <span class="RFC">not required</span> to process or use the referenced
              URI resource, whether or not the resource is listed in the Manifest.
            </p>
          </div>

          <div class="Section">
            <h3 class="SubsubsectionTitle">
              <a class="SectionTitle"
                  href="#TOC2.3.4"
                  id="Section2.3.4"
                  name="Section2.3.4">2.3.4: <span class="Element">img</span> Element</a>
            </h3>

            <p class="Copy">
              The inline element <span class="Element">img</span> <span class="RFC">should</span>
              only be used to refer to images with OPS Core Media Types of GIF (<a href=
              "http://www.w3.org/Graphics/GIF/spec-gif89a.txt"
                 target="_blank"
                 title="GIF specification.">http://www.w3.org/Graphics/GIF/spec-gif89a.txt</a>),
                 PNG (<a href="http://www.ietf.org/rfc/rfc2083.txt"
                 target="_blank"
                 title="PNG specification.">RFC 2083</a>), JPG/JFIF (<a href=
                 "http://www.w3.org/Graphics/JPEG"
                 target="_blank"
                 title="JPEG information page.">http://www.w3.org/Graphics/JPEG</a>) or SVG
                 (<a href="http://www.w3.org/TR/SVG11/"
                 target="_blank"
                 title="SVG soecification.">http://www.w3.org/TR/SVG11/</a>). The <span class=
                 "RFC">required</span> URI attribute, <span class="Attribute">src</span>, is used
                 to reference the image resource, which <span class="RFC">must</span> be listed in
                 the Manifest.
            </p>

            <p class="Copy">
              The <span class="RFC">required</span> <span class="Attribute">alt</span> attribute
              <span class="RFC">should</span> contain a brief and informative textual description
              of the image. This text may be used by Reading Systems as an alternative to, or in
              addition to, displaying the image. The text is also an acceptable fallback for an
              <span class="Element">img</span> with <span class="Attribute">src</span> referencing
              a non-OPS Core Media Type for which no viable fallback was found in the manifest. The
              <span class="Attribute">alt</span> textual description is useful for Reading Systems
              having limited resolution displays, or for non-visual presentation. Use of the
              <span class="Element">object</span> element is the preferred mechanism for including
              non-core media types in an OPS Content Document.
            </p>

            <p class="Copy">
              For long descriptions, the <span class="RFC">optional</span> <span class=
              "Attribute">title</span> attribute <span class="RFC">may</span> be used. Reading
              Systems <span class="RFC">may</span> display the <span class="Attribute">title</span>
              attribute in addition to or in place of the <span class="Attribute">alt</span> text
              or displaying the image.
            </p>

            <p class="Copy">
              For greater accessibility, it is <span class="RFC">strongly recommended</span> that
              OPS Content Document authors include a URI reference in the optional <span class=
              "Attribute">longdesc</span> attribute referencing a resource (such as another OPS
              Content Document in the Publication) describing the image in finer detail. Reading
              System developers are also strongly urged to recognize and render in an appropriate
              fashion (and with accessibility in mind) the resource specified in <span class=
              "Attribute">longdesc</span>. For further information on the use of this attribute and
              related accessibility attributes, see <a href=
              "http://www.w3.org/TR/1999/WAI-WEBCONTENT-19990505/#gl-provide-equivalents"
                 target="_blank"
                 title=
                 "WAI Guidelines.">http://www.w3.org/TR/1999/WAI-WEBCONTENT-19990505/#gl-provide-equivalents</a>.
            </p>
          </div>

          <div class="Section">
            <h3 class="SubsubsectionTitle">
              <a class="SectionTitle"
                  href="#TOC2.3.5"
                  id="Section2.3.5"
                  name="Section2.3.5">2.3.5: <span class="Element">link</span> Element</a>
            </h3>

            <p class="Copy">
              The <span class="Element">link</span> element allows for the specification of various
              relationships with other documents. Reading Systems <span class="RFC">must</span>
              recognize external style sheet references specified via the <span class=
              "Attribute">href</span> attribute and the associated <span class=
              "Attribute">rel</span> attribute (for the values <span class=
              "Attribute">rel=</span><span class="AttributeValue">"stylesheet"</span> and
              <span class="Attribute">rel=</span><span class="AttributeValue">"alternate
              stylesheet"</span>.)
            </p>
          </div>

          <div class="Section">
            <h3 class="SubsubsectionTitle">
              <a class="SectionTitle"
                  href="#TOC2.3.6"
                  id="Section2.3.6"
                  name="Section2.3.6">2.3.6: <span class="Element">object</span> and <span class=
                  "Element">param</span> Elements</a>
            </h3>

            <p class="Copy">
              The <span class="Element">object</span> element is the preferred method for generic
              object inclusion. When adding objects whose data media type is not drawn from the OPS
              Core Media Type list or which reference an <span class="Element">object</span>
              implementation using the <span class="Attribute">classid</span> attribute, the
              <span class="Element">object</span> element <span class="RFC">must</span> specify
              fallback information for the <span class="Element">object</span>, such as another
              <span class="Element">object</span>, an <span class="Element">img</span> element, or
              descriptive text. Inline fallback information is provided as OPS content appearing
              immediately after the final <span class="Element">param</span> element that refers to
              the parent <span class="Element">object</span>. Descriptive text for the <span class=
              "Element">object</span>, using inline content, an included OPS Content Document, or
              some other method, <span class="RFC">should</span> be provided to allow access for
              people who are not able to access non-textual content.
            </p>

            <p class="Copy">
              The <span class="Attribute">classid</span> attribute of an <span class=
              "Element">object</span> gives the URI value of an implementation for the <span class=
              "Element">object</span>. Conformant Reading Systems are <span class="RFC">not
              required</span> to render objects that use external implementations, although they
              may do so. The MIME media type values for the <span class="Attribute">codetype</span>
              and <span class="Attribute">type</span> attributes <span class="RFC">must</span>
              match those specified in the Publication's Manifest.
            </p>

            <p class="Copy">
              The associated <span class="Element">param</span> empty element is used to specify
              initialization values for objects. The <span class="Element">param</span> element
              must only appear before the renderable content of an <span class=
              "Element">object</span>. Reading Systems <span class="RFC">must</span> examine only
              <span class="Element">param</span> elements that are direct children of the
              <span class="Element">object</span>.
            </p>

            <p class="Copy">
              Example:
            </p>

            <pre class="Example">
&lt;object classid="clsid:AFAFAFA-0101-1010-0101-ABABABABABA"
        codebase="http://www.example.com/SomeScriptingLanguage/"&gt;
   &lt;param name="code" value="TicTacToe.class"&gt;
   &lt;param name="codebase" value="html/"&gt;
   &lt;param name="type" value="application/x-somescriptinglanguage"&gt;
   &lt;param name="model" value="models/TicTacToe.model"&gt;
   &lt;param name="scriptable" value="true"&gt;
   &lt;object type="image/png" data="tictactoe.png"&gt;
           Tic-Tac-Toe, a &lt;em&gt;dull&lt;/em&gt; game.
   &lt;/object&gt;
&lt;/object&gt;
</pre>
          </div>

          <div class="Section">
            <h3 class="SubsubsectionTitle">
              <a class="SectionTitle"
                  href="#TOC2.3.7"
                  id="Section2.3.7"
                  name="Section2.3.7">2.3.7: <span class="Element">script</span> and <span class=
                  "Element">noscript</span> Elements</a>
            </h3>

            <p class="Copy">
              Reading Systems <span class="RFC">must not</span><del>, by default,</del> render the
              textual content of the <span class="Element">script</span> element, and <span class=
              "RFC">should not</span> execute the script itself. The content must be readable
              without execution of <span class="Element">script</span> elements.
            </p>

            <p class="Copy">
              If <span class="Element">noscript</span> is included, whose purpose is to display
              some message if the Reading System chooses not to execute the script, it <span class=
              "RFC">must</span> appear after the closing tag of the <span class=
              "Element">script</span> it is associated with. Reading Systems <span class=
              "RFC">must</span>, by default, render the content contained in <span class=
              "Element">noscript</span> if they do not execute <span class="Element">script</span>
              (as is <span class="RFC">recommended</span>), the default of which can be overridden
              by CSS <span class="CSSProperty">display:</span><span class=
              "CSSPropertyValue">none</span>. Note that for XHTML 1.1 conformance the content model
              for noscript is <span class="Element">Block.mix</span> (block level elements plus the
              "level-independent" elements); it cannot directly contain text or inline elements and
              is identical to the content model for <span class="Element">body</span> and
              <span class="Element">blockquote</span>, even if <span class=
              "Element">noscript</span> itself appears inline.
            </p>

            <p class="Copy">
              The attribute <span class="Attribute">type</span>, which specifies the scripting
              language for <span class="Element">script</span>, is <span class=
              "RFC">required</span>.
            </p>

            <p class="Copy">
              One potential problem with <span class="Element">script</span>, whose content model
              is <span class="Element">#PCDATA</span>, is that if the code contains the characters
              "&lt;" and "&amp;", there is a potential conflict with XML. Thus, these characters,
              if used, <span class="RFC">must</span> either be escaped, or put into a <span class=
              "Element">CDATA</span> section. Reading System developers who include script
              execution capability need to be aware of this potential problem.
            </p>
          </div>

          <div class="Section">
            <h3 class="SubsubsectionTitle">
              <a class="SectionTitle"
                  href="#TOC2.3.8"
                  id="Section2.3.8"
                  name="Section2.3.8">2.3.8: <span class="Attribute">type</span> attribute of the
                  <span class="Element">style</span> element</a>
            </h3>

            <p class="Copy">
              The <span class="Attribute">type</span> attribute of the <span class=
              "Element">style</span> element is <span class="RFC">required</span> (per XHTML 1.1
              requirements) and <span class="RFC">must</span> be given the value of <span class=
              "AttributeValue">text/css</span> or the deprecated <span class=
              "AttributeValue">text/x-oeb1-css</span>. For browser rendering of an individual OPS
              Content Document as an XHTML 1.1 document, instances of the deprecated <span class=
              "AttributeValue">text/x-oeb1-css</span> should be changed to <span class=
              "AttributeValue">text/css</span>.
            </p>
          </div>

          <div class="Section">
            <h3 class="SubsubsectionTitle">
              <a class="SectionTitle"
                  href="#TOC2.3.9"
                  id="Section2.3.9"
                  name="Section2.3.9">2.3.9: Value of <span class="Attribute">align</span>
                  attribute</a>
            </h3>

            <p class="Copy">
              The value of <span class="AttributeValue">char</span> for the <span class=
              "Attribute">align</span> attribute is not included in the OPS XHTML subset. To
              achieve similar formatting, use the CSS <span class="CSSProperty">text-align</span>
              property with a <span class="CSSPropertyValue">string</span> value.
            </p>
          </div>
        </div>

        <div class="Section">
          <h2 class="SubsectionTitle">
            <a class="SectionTitle"
                href="#TOC2.4"
                id="Section2.4"
                name="Section2.4">2.4: DTBook Preferred Vocabulary</a>
          </h2>

          <div class="Section">
            <h3 class="SubsubsectionTitle">
              <a class="SectionTitle"
                  href="#TOC2.4.1"
                  id="Section2.4.1"
                  name="Section2.4.1">2.4.1: Introduction</a>
            </h3>

            <p class="Copy">
              DTBook is an XML vocabulary defined in the DAISY/NISO standard, formally, the
              ANSI/NISO Z39.86-2005 Standard. This vocabulary is specifically designed for eBook
              content. Many structures not found in XHTML are included: footnotes, sidebars,
              annotations, page numbers, etc. Identifying the beginning of pages and the number of
              the page in the original print publication enables direct NCX navigation to the
              beginning of each page as reflected in the print publication. These pages will vary
              in size from the screens of information displayed by a typical Reading System. The
              retention of print page marking will enable a user to move to the identical location
              as someone who may be using a printed book.
            </p>

            <p class="Copy">
              It is strongly <span class="RFC">recommended</span> that Content Providers select
              this XML Preferred Vocabulary for their educational publications and for content that
              is highly structured.
            </p>

            <p class="Copy">
              Many publishers may already have their content in DTBook as a result of the U.S.
              Individuals with Disabilities Education Improvement Act (IDEIA) of 2004 or other
              similar international legislation. Transforming it into an OPS publication can be
              accomplished with ease. Having the publication available using the DTBook vocabulary
              may help publishers market their publications to all students in the education market
              place, including those with print disabilities.
            </p>

            <p class="Copy">
              <a href="http://www.niso.org/standards/resources/Z39-86-2005.html#Text"
                 target="_blank"
                 title="DTBook - Content Format for Text">Section 4</a> of the DAISY/NISO Standard
                 defines the DTBook DTD. This can be found on the NISO Web site at: <a href=
                 "http://www.niso.org/standards/resources/Z39-86-2005.html"
                 target="_blank"
                 title=
                 "DTBook specification.">http://www.niso.org/standards/resources/Z39-86-2005.html</a>.
            </p>

            <p class="Copy">
              Additional information such as DTDs, issues tracking, samples and more can be found
              on the DAISY Web site at: <a href="http://www.daisy.org/z3986/"
                 target="_blank"
                 title="DAISY website.">http://www.daisy.org/z3986/</a>.
            </p>
          </div>

          <div class="Section">
            <h3 class="SubsubsectionTitle">
              <a class="SectionTitle"
                  href="#TOC2.4.2"
                  id="Section2.4.2"
                  name="Section2.4.2">2.4.2: DTBook Usage Requirements</a>
            </h3>

            <p class="Copy">
              DTBook, as described in Section 4 of the DAISY/NISO Standard, <span class=
              "RFC">must</span> be followed in DTBook OPS Publications. The content <span class=
              "RFC">must</span> validate against the <a href=
              "http://www.daisy.org/z3986/2005/dtbook-2005-2.dtd"
                 target="_blank"
                 title="DTBook DTD.">dtbook-2005-2.dtd</a>, which was the latest version at the
                 time of this writing. This DTD version, all previous versions, and all future
                 versions will be available on the <a href="http://www.daisy.org/"
                 target="_blank"
                 title="DAISY website."><del>Daisy</del><ins>DAISY</ins> website</a>. This will
                 ensure that OPS Publications created under any version of the DTD remain valid.
            </p>

            <p class="Copy">
              It is essential that the semantics of the DTBook elements be applied correctly. To
              assist with this, a set of "Structure Guidelines" has been created. Documents created
              conforming to DTBook <span class="RFC">should</span> use the Structure Guidelines for
              information regarding the correct application of the semantics of the elements. The
              Structure Guidelines can be found at: <a href="http://www.daisy.org/z3986/structure/"
                 target="_blank"
                 title="DTBook Structure Guidelines">http://www.daisy.org/z3986/structure/</a>.
            </p>

            <div class="Section">
              <h4 class="SubsubsubsectionTitle">
                <a class="SectionTitle"
                    href="#TOC2.4.2.1"
                    id="Section2.4.2.1"
                    name="Section2.4.2.1">2.4.2.1: Exceptions to Section 4 of the DAISY/NISO
                    Standard</a>
              </h4>

              <p class="Copy">
                There is a single attribute on elements in DTBook called <span class=
                "Attribute">smilref</span>. This attribute is used for SMIL <ins>(<a href=
                "http://www.w3.org/TR/2005/REC-SMIL2-20050107/"
                   target="_blank"
                   title=
                   "The SMIL specification.">http://www.w3.org/TR/2005/REC-SMIL2-20050107/</a>)</ins>
                   coordination. SMIL is not supported in OPS Publications. Leaving this attribute
                   out of DTBook documents in OPS Publications <del><span class="RFC">must
                   not</span></del> <ins>will not</ins> cause validation errors.
              </p>
            </div>
          </div>
        </div>

        <div class="Section">
          <h2 class="SubsectionTitle">
            <a class="SectionTitle"
                href="#TOC2.5"
                id="Section2.5"
                name="Section2.5">2.5: SVG</a>
          </h2>

          <p class="Copy">
            Many images, such as maps, charts, graphs, etc., originate from vector graphics
            systems, not photographs. Such images can be represented in a vector (as opposed to
            raster) format that describes the image in terms of lines, curves and absolutely
            positioned blocks of text (as opposed to an array of pixels). Replacing raster images
            with vector ones makes documents more accessible and searchable. This additional effort
            on the part of Reading Systems and authors can improve accessibility significantly.
            Vector images also improve the visual quality of documents (since vector images are
            inherently scalable) and tend to decrease document sizes.
          </p>

          <p class="Copy">
            OPS Reading Systems <span class="RFC">must</span> support SVG (Scalable Vector
            Graphics) as an OPS Core Media Type.
          </p>

          <div class="Section">
            <h3 class="SubsubsectionTitle">
              <a class="SectionTitle"
                  href="#TOC2.5.1"
                  id="Section2.5.1"
                  name="Section2.5.1">2.5.1: General Notes on SVG Usage</a>
            </h3>

            <p class="Copy">
              OPS supports the full SVG 1.1 Recommendation. The only exception is that since OPS is
              not targeting interactive content. SVG animation and scripting features are not
              supported and <span class="RFC">must not</span> be used by publication authors; a
              Reading System <span class="RFC">should not</span> render such content. CSS styling
              of SVG <span class="RFC">must</span> be fully supported.
            </p>

            <p class="Copy">
              Text in SVG images <span class="RFC">should</span> be selectable and searchable. SVG
              images <span class="RFC">may</span> contain links (<span class="Element">a</span>
              elements) and thus may be used for navigation. If a Reading System supports "tabbing"
              through links, SVG links <span class="RFC">must</span> be included.
            </p>

            <p class="Copy">
              Inline SVG is only supported within documents using the XHTML Preferred Vocabulary.
              It <span class="RFC">must not</span> be used within DTBook documents.
            </p>
          </div>

          <div class="Section">
            <h3 class="SubsubsectionTitle">
              <a class="SectionTitle"
                  href="#TOC2.5.2"
                  id="Section2.5.2"
                  name="Section2.5.2">2.5.2: SVG’s Use as a Standalone Image File</a>
            </h3>

            <p class="Copy">
              SVG content can be used in OPS in any place where other image types can be used. This
              includes:
            </p>

            <ul>
              <li>References from XHTML <span class="Element">img</span> and <span class="Element">
                object</span> elements
              </li>

              <li>
                <ins>References from DTBook <span class="Element">img</span> elements</ins>
              </li>

              <li>References from SVG <span class="Element">image</span> elements
              </li>

              <li>References from CSS properties that take an image URI as a parameter
              </li>
            </ul>

            <p class="Copy">
              To ensure maximum portability, the dimensions of SVG images <span class=
              "RFC">should</span> always be specified on the top-level SVG element . As with bitmap
              images, referencing elements <span class="RFC">may</span> override an SVG image’s
              dimensions causing it to scale.
            </p>

            <p class="Copy">
              Each SVG image is considered a separate document for the purposes of styling.
              Referencing document style sheets do not apply to referenced SVG images, nor are CSS
              properties inherited by SVG images. Common styles <span class="RFC">should</span> be
              achieved by creating style sheets that are referenced by both SVG and XHTML. Note
              that this is consistent with situations in which an <span class=
              "Element">object</span> element references an XHTML element.
            </p>
          </div>

          <div class="Section">
            <h3 class="SubsubsectionTitle">
              <a class="SectionTitle"
                  href="#TOC2.5.3"
                  id="Section2.5.3"
                  name="Section2.5.3">2.5.3: Mixing SVG and XHTML Mark-up in the Same Document</a>
            </h3>

            <p class="Copy">
              The other way of using SVG is to embed SVG mark-up directly in XHTML mark-up. The SVG
              root element (<span class="Element">svg</span>) <span class="RFC">must</span> be
              considered replaced by its content in the CSS layout, so <span class=
              "Element">svg</span> elements <span class="RFC">may</span> be used anywhere XHTML
              <span class="Element">img</span> <del>or <span class="Element">object</span></del>
              elements could be used. Other SVG elements <span class="RFC">may</span> only be used
              as <span class="Element">svg</span> element descendants. Since SVG and XHTML elements
              have different namespaces, care needs to be taken to assign proper namespaces to each
              element using namespace prefixes or the <span class="Attribute">xmlns</span>
              attribute.
            </p>

            <p class="Copy">
              In this case, there is only one document and CSS style sheets apply to the document
              as a whole (including cascade and inheritance). In the usual manner, each element
              only makes use of the properties that are applicable to it. The root <span class=
              "Element">svg</span> element’s role in CSS layout is determined by the <span class=
              "CSSProperty">display</span>, <span class="CSSProperty">float</span> and <span class=
              "CSSProperty">position</span> properties, just like it works for the <span class=
              "Element">img</span> element. SVG image dimensions are determined by the <span class=
              "Attribute">width</span> and <span class="Attribute">height</span> attributes on the
              root <span class="Element">svg</span> element (which are considered to be the
              replaced element’s intrinsic dimensions in the CSS box layout) and the <span class=
              "CSSProperty">width</span> and <span class="CSSProperty">height</span> properties
              assigned by CSS. See <a href="http://www.w3.org/TR/CSS2/conform.html"
                 target="_blank"
                 title="CSS2 Conformance.">http://www.w3.org/TR/CSS2/conform.html</a> for a
                 definition of "replaced element" and "intrinsic dimensions." For portability,
                 authors <span class="RFC">should</span> avoid assigning XHTML-only CSS properties
                 to SVG elements and vise-versa.
            </p>
          </div>
        </div>

        <div class="Section">
          <h2 class="SubsectionTitle">
            <a class="SectionTitle"
                href="#TOC2.6"
                id="Section2.6"
                name="Section2.6">2.6: XML Islands</a>
          </h2>

          <p class="Copy">
            This section describes the markup and a processing model for the inclusion of generic
            XML content in OPS Publications.
          </p>

          <div class="Section">
            <h3 class="SubsubsectionTitle">
              <a class="SectionTitle"
                  href="#TOC2.6.1"
                  id="Section2.6.1"
                  name="Section2.6.1">2.6.1: Introduction to XML Islands</a>
            </h3>

            <p class="Copy">
              This section defines a method of including generic XML markup in OPS Publications.
              The motivation is to achieve the maximum backwards, sideways, and forwards
              compatibility with other XML vocabularies, including Extended OEBPS, as defined in
              <a href="http://www.idpf.org/oebps/oebps1.2/download/oeb12-xhtml.htm#sec1.4.1"
                 target="_blank"
                 title="OEBPS 1.2 - Document and Conformance Section">OEBPS 1.2</a>.
            </p>

            <p class="Copy">
              This is consistent with the <a href=
              "http://www.idpf.org/oebps/oebps1.2/download/oeb12-xhtml.htm#sec1.4.3"
                 target="_blank"
                 title="OEBPS 1.2 - Compatibility with Future Versions">stated future
                 directions</a> of OEBPS 1.2.
            </p>

            <p class="Copy">
              To that end, this document introduces the idea of "XML Islands." Two variants exist:
            </p>

            <ul>
              <li>Out-Of-Line XML Islands
              </li>

              <li>Inline XML Islands
              </li>
            </ul>

            <p class="Copy">
              Out-Of-Line XML Islands are any complete XML document that is not authored in one of
              the Preferred Vocabularies (i.e. DTBook or XHTML) or uses an Extended Module in an
              otherwise Preferred Vocabulary document.
            </p>

            <p class="Copy">
              An Inline XML Island is an XML document fragment using a non-Preferred Vocabulary or
              using an Extended Module of a Preferred Vocabulary that exists within an XHTML
              Preferred Vocabulary document within an OPS Publication. Inline XML Islands are also
              namespace-qualified to the OPS namespace and are not contained within <span class=
              "Element">object</span> elements.
            </p>

            <p class="Copy">
              Inline XML Islands <span class="RFC">must not</span> be used within documents using
              the DTBook Preferred Vocabulary; they <span class="RFC">must</span> only be used
              within XHTML documents.
            </p>

            <div class="Section">
              <h4 class="SubsubsubsectionTitle">
                <a class="SectionTitle"
                    href="#TOC2.6.1.1"
                    id="Section2.6.1.1"
                    name="Section2.6.1.1">2.6.1.1: Use Cases</a>
              </h4>

              <p class="Copy">
                Following are the use cases that justify the existence of XML Islands in OPS:
              </p>

              <ol>
                <li>
                  <span class="Emphasis">Backwards Compatibility:</span> There are an unknown
                  number of documents that use Extended OEBPS 1.2 Documents which could be used in
                  new Reading Systems. This document describes a method in which such documents
                  could be used with minimal additions such as a few extra attributes in the OPS
                  manifest, the addition of a single namespace declaration and/or the creation of a
                  CSS style sheet.
                </li>

                <li>
                  <span class="Emphasis">Sideways Compatibility:</span> There are innumerable
                  documents using non-Preferred XML vocabularies which exist and could be used in
                  Reading Systems. This can be accomplished using the same methodology described
                  above or using customized display semantics according to methods not available in
                  a baseline OPS Reading System in conjunction with fallbacks to OPS Preferred
                  Vocabularies.
                </li>

                <li>
                  <span class="Emphasis">Forwards Compatibility:</span> Experimentation with
                  vocabularies that do not yet exist is enabled.
                </li>
              </ol>
            </div>

            <div class="Section">
              <h4 class="SubsubsubsectionTitle">
                <a class="SectionTitle"
                    href="#TOC2.6.1.2"
                    id="Section2.6.1.2"
                    name="Section2.6.1.2">2.6.1.2: Display Guidelines</a>
              </h4>

              <p class="Copy">
                OPS Reading Systems <span class="RFC">must</span> follow these steps in handling
                the display of correctly marked up XML Islands:
              </p>

              <ol>
                <li>
                  <span class="Emphasis">Semantic Styling:</span> A Reading System <span class=
                  "RFC">may</span> do more with XML Island content than provided for by the
                  baseline requirements of OPS. This could include expanded rendering capabilities
                  based on the Reading System’s intrinsic knowledge of the XML Island vocabulary
                  (e.g. a TEI-reader, or a MathML reader).
                </li>

                <li>
                  <span class="Emphasis">Fallback to OPS:</span> A Reading System <span class=
                  "RFC">must</span> use one of the fallback mechanisms if it lacks intrinsic
                  knowledge of an XML Island’s vocabulary.
                </li>
              </ol>

              <p class="Copy">
                This allows the inclusion of non-Preferred Vocabulary content in a standardized way
                that lets a Reading System to do more than OPS requires as a baseline, while still
                allowing baseline Reading Systems to handle such content in a reasonable manner.
              </p>
            </div>
          </div>

          <div class="Section">
            <h3 class="SubsubsectionTitle">
              <a class="SectionTitle"
                  href="#TOC2.6.2"
                  id="Section2.6.2"
                  name="Section2.6.2">2.6.2: Out-of-Line XML Islands</a>
            </h3>

            <p class="Copy">
              An Out-Of-Line XML Island is a complete XML document that is not authored in one of
              the Preferred Vocabularies or uses an Extended Module in an otherwise Preferred
              Vocabulary document. Including an Out-Of-Line XML Island requires several
              declarations in various parts of the Publication.
            </p>

            <div class="Section">
              <h4 class="SubsubsubsectionTitle">
                <a class="SectionTitle"
                    href="#TOC2.6.2.1"
                    id="Section2.6.2.1"
                    name="Section2.6.2.1">2.6.2.1: Document Requirements</a>
              </h4>

              <p class="Copy">
                An Out-Of-Line XML Island must be a valid XML document<del>, as defined in XML
                1.1</del> <ins>(according to its schema)</ins> and meet the other conformance
                requirements defined in section "<a href="#Section1.4.1.4"
                   title="Out-of-Line XML Island Content Document Requirements">Out-of-Line XML
                   Island Content Document Requirements.</a>"
              </p>

              <p class="Copy">
                The following is a simple Out-Of-Line XML Island:
              </p>

              <pre class="Example">
&lt;?xml version="1.0"?&gt;
&lt;!DOCTYPE example SYSTEM "example.dtd"&gt;
&lt;example&gt;
   &lt;title&gt;This Is An Example&lt;/title&gt;
   &lt;paragraph&gt;This is a paragraph with a &lt;huge&gt;big&lt;/huge&gt; section
   of text that could be styled with OPS CSS!&lt;/paragraph&gt;
&lt;/example&gt;
</pre>
            </div>

            <div class="Section">
              <h4 class="SubsubsubsectionTitle">
                <a class="SectionTitle"
                    href="#TOC2.6.2.2"
                    id="Section2.6.2.2"
                    name="Section2.6.2.2">2.6.2.2: Fallback Requirements</a>
              </h4>

              <p class="Copy">
                The inclusion of an Out-Of-Line XML Island requires certain attributes and
                attribute values within a publication’s manifest to specify fallback information
                for Reading Systems that cannot natively process the Out-Of-Line XML Island’s
                vocabulary. See the <a href="http://www.idpf.org/opf/opf2.0/download/"
                   target="_blank"
                   title="OPF specification.">OPF specification</a>.
              </p>
            </div>

            <div class="Section">
              <h4 class="SubsubsubsectionTitle">
                <a class="SectionTitle"
                    href="#TOC2.6.2.3"
                    id="Section2.6.2.3"
                    name="Section2.6.2.3">2.6.2.3: Linking Requirements</a>
              </h4>

              <p class="Copy">
                Links that point into Out-Of-Line XML Islands <span class="RFC">must</span> be
                resolved by a compliant OPS Reading System as follows:
              </p>

              <div class="Section">
                <h5 class="SubsubsubsubsectionTitle">
                  <a class="SectionTitle"
                      href="#TOC2.6.2.3.1"
                      id="Section2.6.2.3.1"
                      name="Section2.6.2.3.1">2.6.2.3.1: Document-Level Links</a>
                </h5>

                <p class="Copy">
                  Links that point at an entire document in the publication <span class=
                  "RFC">must</span> automatically resolve to the fallback document if the fallback
                  document is used.
                </p>

                <p class="Copy">
                  <span class="Emphasis">Link Source:</span>
                </p>

                <pre class="Example">
...&lt;a href=<del>”</del><ins>"</ins>chapter2.xml<del>”</del><ins>"</ins>&gt;Chapter 2&lt;/a&gt;...
</pre>
                <p class="Copy">
                  <span class="Emphasis">Preferred Document -</span> <span class=
                  "File">chapter2.xml</span><span class="Emphasis">:</span>
                </p>

                <pre class="Example">
        &lt;chapter&gt;
                &lt;title&gt;Chapter 2&lt;/title&gt;
                ...
        &lt;/chapter&gt;
</pre>
                <p class="Copy">
                  <span class="Emphasis">Fallback Document -</span> <span class=
                  "File">chapter2.html</span><span class="Emphasis">:</span>
                </p>

                <pre class="Example">
&lt;html&gt;
        &lt;head&gt;
                &lt;title&gt;Chapter 2&lt;/title&gt;
        &lt;/head&gt;
        &lt;body&gt;
                ...
        &lt;/body&gt;
&lt;/html&gt;
</pre>
                <p class="Copy">
                  <span class="Emphasis">Manifest Fragment:</span>
                </p>

                <pre class="Example">
&lt;item href="chapter2.xml" id="chapter2"
      media-type="text/xml"
      required-namespace="http://www.example.com/chapter"
      fallback="chapter2fallback"/&gt;
&lt;item href="chapter2.html" id="chapter2fallback"
      <ins>media-type="application/xhtml+xml"</ins>/&gt;
</pre>
                <p class="Copy">
                  In this example, there are two possible behaviors. If the Reading System is
                  capable of processing the document format of <span class=
                  "File">chapter2.xml</span> then the link resolves to <span class=
                  "File">chapter2.xml</span>. Otherwise, the link resolves to the fallback for
                  <span class="File">chapter2.xml</span>, which is <span class=
                  "File">chapter2.html</span>.
                </p>
              </div>

              <div class="Section">
                <h5 class="SubsubsubsubsectionTitle">
                  <a class="SectionTitle"
                      href="#TOC2.6.2.3.2"
                      id="Section2.6.2.3.2"
                      name="Section2.6.2.3.2">2.6.2.3.2: Fragment Links</a>
                </h5>

                <p class="Copy">
                  Links that include <a href="#Section1.2"
                     title="Definitions">document fragments</a> <span class="RFC">must</span>
                     resolve to the fallback item, using the same fragment identifier. In the event
                     that the fragment identifier does not exist in the fallback, the Reading
                     System <span class="RFC">must</span> place the link entry point at the start
                     of the fallback document.
                </p>
              </div>
            </div>
          </div>

          <div class="Section">
            <h3 class="SubsubsectionTitle">
              <a class="SectionTitle"
                  href="#TOC2.6.3"
                  id="Section2.6.3"
                  name="Section2.6.3">2.6.3: Inline XML Islands</a>
            </h3>

            <p class="Copy">
              An inline XML Island is an XML document fragment using a non-Preferred Vocabulary or
              using an Extended Module of a Preferred Vocabulary that exists within an XHTML
              Preferred Vocabulary document within an OPS Publication.
            </p>

            <p class="Copy">
              Processing Inline XML Islands is more complex than processing Out-Of-Line XML
              Islands, due to processing and display requirements. Out-Of-Line XML Islands are full
              XML documents, whose fallback options are defined in the <a href=
              "http://www.idpf.org/opf/opf2.0/download/OPF2.0.html#Section2.3.1"
                 target="_blank"
                 title="OPF fallback section.">OPF Package Document</a>. Inline XML Islands are
                 handled via a markup structure designed to simulate the common programming concept
                 of a "switch" statement.
            </p>

            <div class="Section">
              <h4 class="SubsubsubsectionTitle">
                <a class="SectionTitle"
                    href="#TOC2.6.3.1"
                    id="Section2.6.3.1"
                    name="Section2.6.3.1">2.6.3.1: The <span class="Element">switch</span> Element
                    and Contained Elements</a>
              </h4>

              <p class="Copy">
                The switch element is a concept used in both <a href="http://www.w3.org/TR/SVG11/"
                   target="_blank"
                   title="SVG 1.1 specification.">SVG 1.1</a> and <del><a href=
                   "http://www.w3.org/TR/2005/REC-SMIL2-20051213/"
                   target="_blank"
                   title="SMIL 2.1 specification.">SMIL 2.1</a></del><ins><a href=
                   "http://www.w3.org/TR/SMIL2/"
                   target="_blank"
                   title="SMIL 2.1 specification.">SMIL 2.x</a></ins>; however, OPS has
                   requirements that are not identical to those specifications. As a result, the
                   OPS implementation of the switch concept differs. Specifically, author intent is
                   required in an explicit and clear fashion. In addition, the concept of a base
                   fallback mechanism is provided. The normative definition of the <span class=
                   "Element">switch</span> element and its contained elements can be found in the
                   <a href="#AppendixB"
                   title="The OPS Schema.">OPS Schema</a>.
              </p>

              <p class="Copy">
                The <span class="Element">switch</span> element and all contained elements reside
                in the OPS Namespace (<span class="Namespace">http://www.idpf.org/2007/ops</span>).
              </p>

              <div class="Section">
                <h5 class="SubsubsubsubsectionTitle">
                  <a class="SectionTitle"
                      href="#TOC2.6.3.1.1"
                      id="Section2.6.3.1.1"
                      name="Section2.6.3.1.1">2.6.3.1.1: <span class="Element">switch</span>
                      Element</a>
                </h5>

                <p class="Copy">
                  The <span class="Element">switch</span> element is the containing element for an
                  Inline XML Island. It contains zero or more <span class="Element">case</span>
                  elements, and must contain one <span class="Element">default</span> element. The
                  element names have been selected to be easily understood by those familiar with
                  the "switch" feature of many programming languages.
                </p>

                <p class="Copy">
                  An example of markup using the <span class="Element">switch</span> element
                  follows:
                </p>

                <pre class="Example">
&lt;ops:switch id="mathmlSwitch"&gt;

   &lt;ops:case required-namespace="http://www.w3.org/1998/Math/MathML"&gt;
      &lt;math xmlns="http://www.w3.org/1998/Math/MathML"&gt;
         &lt;mrow&gt;
            &lt;mn&gt;2&lt;/mn&gt;
            &lt;mo&gt;&amp;InvisibleTimes;&lt;/mo&gt;
            &lt;mi&gt;x&lt;/mi&gt;
         &lt;/mrow&gt;
         &lt;mrow&gt;
            &lt;mo&gt;+&lt;/mo&gt;
            &lt;mi&gt;y&lt;/mi&gt;
            &lt;mo&gt;-&lt;/mo&gt;
            &lt;mi&gt;z&lt;/mi&gt;
         &lt;/mrow&gt;
      &lt;/math&gt;
   &lt;/ops:case&gt;

   &lt;ops:default&gt;
      &lt;p&gt;2x + y - z&lt;/p&gt;
   &lt;/ops:default&gt;

&lt;/ops:switch&gt;
</pre>
              </div>

              <div class="Section">
                <h5 class="SubsubsubsubsectionTitle">
                  <a class="SectionTitle"
                      href="#TOC2.6.3.1.2"
                      id="Section2.6.3.1.2"
                      name="Section2.6.3.1.2">2.6.3.1.2: <span class="Element">case</span>
                      Element</a>
                </h5>

                <p class="Copy">
                  The <span class="Element">case</span> element is used to contain non-Preferred
                  Vocabulary or Extended Module markup. There are zero or more <span class=
                  "Element">case</span> elements in a <span class="Element">switch</span> element.
                  The <span class="Element">case</span> element contains no content from the OPS
                  namespace. This does not preclude it from containing content that is outside the
                  OPS namespace, which is typically the case.
                </p>

                <p class="Copy">
                  An OPS Reading System <span class="RFC">must not</span> invalidate a document and
                  <span class="RFC">must</span> display nothing if a <span class=
                  "Element">case</span> element contains no content.
                </p>

                <div class="Section">
                  <h6 class="SubsubsubsubsubsectionTitle">
                    <a class="SectionTitle"
                        href="#TOC2.6.3.1.2.1"
                        id="Section2.6.3.1.2.1"
                        name="Section2.6.3.1.2.1">2.6.3.1.2.1: <span class=
                        "Attribute">required-namespace</span> Attribute</a>
                  </h6>

                  <p class="Copy">
                    The <span class="Attribute">required-namespace</span> attribute specifies the
                    namespace of the XML vocabulary that the Reading System <span class=
                    "RFC">must</span> support in order to process the content of the <span class=
                    "Element">case</span> element. A Reading System <span class="RFC">should</span>
                    process the content of the first <span class="Element">case</span> element that
                    has a <span class="Attribute">required-namespace</span> attribute value that it
                    supports. Note that processing of extra-OPS XML vocabularies is <span class=
                    "RFC">not required</span>. Only the island’s fallback (<span class=
                    "Element">default</span> element) <span class="RFC">must</span> be processed.
                  </p>

                  <p class="Copy">
                    Documents that have a root element in the XHTML namespace <span class=
                    "RFC">must not</span> use elements outside the XHTML namespace and, where
                    allowed, the SVG namespace unless they are either specifically allowed there
                    (e.g. SVG <span class="Element">metadata</span> element) or they are
                    descendants of a <span class="Element">case</span> element that has a matching
                    <span class="Attribute">required-namespace</span> attribute value.
                  </p>
                </div>

                <div class="Section">
                  <h6 class="SubsubsubsubsubsectionTitle">
                    <a class="SectionTitle"
                        href="#TOC2.6.3.1.2.2"
                        id="Section2.6.3.1.2.2"
                        name="Section2.6.3.1.2.2">2.6.3.1.2.2: <span class=
                        "Attribute">required-modules</span> attribute</a>
                  </h6>

                  <p class="Copy">
                    Some XML vocabularies are broken down into distinct modules, which <span class=
                    "RFC">may</span> be supported in part or in whole by a compliant application.
                    These vocabularies have a set of named modules defined in their specification,
                    and some or all of these modules are <span class="RFC">optional</span> – such
                    <span class="RFC">optional</span> modules are deemed Extended Modules in the
                    specification.
                  </p>

                  <p class="Copy">
                    A modularized XML vocabulary is considered supported by the Reading System if
                    the Reading System supports the least number of modules required by the
                    vocabulary's specification – supporting at least all non-Extended Modules of
                    the XML vocabulary.
                  </p>

                  <p class="Copy">
                    An Inline XML Island authored in a Preferred Vocabulary by definition
                    incorporates use of Extended Modules. In this case, and with non-Preferred
                    Vocabulary islands utilizing Extended Modules, the <span class=
                    "Attribute">required-modules</span> attribute <span class="RFC">must</span> be
                    present along with the <span class="Attribute">required-namespace</span>
                    attribute. The attribute value for <span class=
                    "Attribute">required-modules</span> <span class="RFC">must</span> be a
                    comma-separated list containing the name(s) of the Extended Modules used in the
                    Inline XML Island. The names of the modules are not case-sensitive, unless
                    specifically defined otherwise in the XML vocabulary specification. Spaces in
                    module names <span class="RFC">must</span> be replaced with "-" for listing in
                    the <span class="Attribute">required-modules</span> attribute value. For XHTML,
                    in the context of OPS, the Extended Modules include <span class=
                    "AttributeValue">ruby</span>, <span class="AttributeValue">forms</span>,
                    <span class="AttributeValue">server-side-image-map</span>, and <span class=
                    "AttributeValue">intrinsic-events</span>.
                  </p>

                  <p class="Copy">
                    Note that listing the names of non-Extended Modules in a <span class=
                    "Attribute">required-modules</span> attribute value is also allowed; such
                    modules are always considered to be supported if the XML vocabulary is
                    supported. This can be useful both for clarity and in the case where there is a
                    possibility that some modules may become <span class="RFC">optional</span> in
                    the later revisions of the specification (e.g. the currently deprecated Style
                    Attribute XHTML module in OPS).
                  </p>

                  <p class="Copy">
                    It is allowed, and sometimes useful, to provide a <span class=
                    "Attribute">required-modules</span> attribute on a <span class=
                    "Element">case</span> specifying a non-Preferred Vocabulary Inline XML island —
                    either for clarity or to specify Extended Modules used in the non-Preferred
                    Vocabulary.
                  </p>

                  <p class="Copy">
                    An example of using <span class="Attribute">required-modules</span> to specify
                    an XHTML module outside of OPS’s core supported modules follows:
                  </p>

                  <pre class="Example">
&lt;ops:switch id="XHTMLServerSideSwitch" xmlns:ops="http://www.idpf.org/2007/ops"&gt;
        &lt;ops:case required-namespace="http://www.w3.org/1999/xhtml"
                required-modules="server-side-image-map"&gt;
                &lt;a href="http://www.example.com/examplemap.map"&gt;
                &lt;img src="example.gif" ismap="ismap"
                        title="Example Map"
                        alt="A picture of an example." /&gt;
                &lt;/a&gt;
        &lt;/ops:case&gt;
        &lt;ops:default&gt;
                &lt;img src="example.gif" usemap="map"
                        title="Example Map"
                        alt="A picture of an example." /&gt;
                &lt;map name="map"&gt;
                        &lt;area href="example1.html"
                                alt="Link to the first example."
                                shape="rect" coords="0,0,118,28" /&gt;
                        &lt;area href="example2.html"
                                alt="Link to the second example"
                                shape="rect" coords="184,0,276,28" /&gt;
                &lt;/map&gt;
        &lt;/ops:default&gt;
&lt;/ops:switch&gt;
</pre>
                </div>
              </div>

              <div class="Section">
                <h5 class="SubsubsubsubsectionTitle">
                  <a class="SectionTitle"
                      href="#TOC2.6.3.1.3"
                      id="Section2.6.3.1.3"
                      name="Section2.6.3.1.3">2.6.3.1.3: <span class="Element">default</span>
                      Element</a>
                </h5>

                <p class="Copy">
                  The <span class="Element">default</span> element is nearly identical to the
                  <span class="Element">case</span> element. The purpose of the <span class=
                  "Element">default</span> element is to provide compliant markup as a baseline (or
                  fallback) for display of the <span class="Element">switch</span>. The
                  <span class="Element">default</span> element <span class="RFC">must</span>
                  contain only XML nodes that would be allowed at the point of the document where
                  its parent <span class="Element">switch</span> element was used. More precisely,
                  a document is considered valid if and only if replacing all <span class=
                  "Element">switch</span> elements with the content of their child <span class=
                  "Element">default</span> elements yields a valid document.
                </p>
              </div>
            </div>

            <div class="Section">
              <h4 class="SubsubsubsectionTitle">
                <a class="SectionTitle"
                    href="#TOC2.6.3.2"
                    id="Section2.6.3.2"
                    name="Section2.6.3.2">2.6.3.2: Processing Inline XML Islands</a>
              </h4>

              <p class="Copy">
                Inline XML Islands <span class="RFC">must</span> be processed via the markup
                definitions found in the switch element and its contained elements.
              </p>
            </div>

            <div class="Section">
              <h4 class="SubsubsubsectionTitle">
                <a class="SectionTitle"
                    href="#TOC2.6.3.3"
                    id="Section2.6.3.3"
                    name="Section2.6.3.3">2.6.3.3: Displaying Inline XML Islands</a>
              </h4>

              <div class="Section">
                <h5 class="SubsubsubsubsectionTitle">
                  <a class="SectionTitle"
                      href="#TOC2.6.3.3.1"
                      id="Section2.6.3.3.1"
                      name="Section2.6.3.3.1">2.6.3.3.1: Advanced Display Semantics</a>
                </h5>

                <p class="Copy">
                  Reading Systems <span class="RFC">must</span> process <span class=
                  "Element">case</span> elements in the order they appear, and <span class=
                  "RFC">should</span> render the content of the first supported <span class=
                  "Element">case</span> element recognized (i.e. the Reading System supports the
                  vocabulary specified in the <span class="Attribute">required-namespace</span>). A
                  Reading System must render only a single <span class="Element">case</span> or
                  <span class="Element">default</span> element within a <span class=
                  "Element">switch</span>, ignoring the contents of all other <span class=
                  "Element">case</span> and <span class="Element">default</span> elements.
                </p>

                <p class="Copy">
                  Reading Systems that do support the vocabularies of any of the <span class=
                  "Element">case</span> elements <span class="RFC">must</span> render the contents
                  of the <span class="Element">default</span> element.
                </p>
              </div>

              <div class="Section">
                <h5 class="SubsubsubsubsectionTitle">
                  <a class="SectionTitle"
                      href="#TOC2.6.3.3.2"
                      id="Section2.6.3.3.2"
                      name="Section2.6.3.3.2">2.6.3.3.2: Styling of Islands</a>
                </h5>

                <p class="Copy">
                  When styling is applied to a document that contains Inline XML Islands, style
                  sheet cascading and inheritance rules are used for the complete document tree.
                  However, OPS <span class="Element">switch</span>, <span class=
                  "Element">case</span> and <span class="Element">default</span> elements
                  <span class="RFC">must</span> ignore all styling properties that are assigned to
                  them. In particular, those elements <span class="RFC">must not</span> create any
                  boxes (e.g. in terms of CSS box layout), as XHTML elements would.
                </p>
              </div>
            </div>

            <div class="Section">
              <h4 class="SubsubsubsectionTitle">
                <a class="SectionTitle"
                    href="#TOC2.6.3.4"
                    id="Section2.6.3.4"
                    name="Section2.6.3.4">2.6.3.4: Linking Considerations</a>
              </h4>

              <p class="Copy">
                Deep linking into the content of Inline XML Islands cannot be accomplished
                consistently because various alternative Inline XML Islands <span class="RFC">must
                not</span> contain elements with identical <span class="Attribute">id</span>
                attributes. It is therefore not possible to provide references that will resolve
                regardless of the <span class="Element">case</span> element selected for display.
              </p>

              <div class="Section">
                <h5 class="SubsubsubsubsectionTitle">
                  <a class="SectionTitle"
                      href="#TOC2.6.3.4.1"
                      id="Section2.6.3.4.1"
                      name="Section2.6.3.4.1">2.6.3.4.1: Linking to <span class=
                      "Element">switch</span> Elements</a>
                </h5>

                <p class="Copy">
                  Reading Systems <span class="RFC">must</span> recognize and display links that
                  target <span class="Element">switch</span> elements even though the <span class=
                  "Element">switch</span> has no display characteristics of its own.
                </p>
              </div>

              <div class="Section">
                <h5 class="SubsubsubsubsectionTitle">
                  <a class="SectionTitle"
                      href="#TOC2.6.3.4.2"
                      id="Section2.6.3.4.2"
                      name="Section2.6.3.4.2">2.6.3.4.2: Broken Links</a>
                </h5>

                <p class="Copy">
                  Links into Inline XML Islands <span class="RFC">must</span> be dropped without
                  warning or error as they would be in a typical XHTML-compliant browser.
                </p>
              </div>
            </div>

            <div class="Section">
              <h4 class="SubsubsubsectionTitle">
                <a class="SectionTitle"
                    href="#TOC2.6.3.5"
                    id="Section2.6.3.5"
                    name="Section2.6.3.5">2.6.3.5: NCX Requirements</a>
              </h4>

              <p class="Copy">
                Links from an NCX to Inline XML Islands <span class="RFC">must</span> work
                identically to other links to Inline XML Islands.
              </p>
            </div>
          </div>
        </div>

        <div class="Section">
          <h2 class="SubsectionTitle">
            <a class="SectionTitle"
                href="#TOC2.7"
                id="Section2.7"
                name="Section2.7">2.7: Rendering of Documents on Reading Systems</a>
          </h2>

          <p class="Copy">
            A number of elements and attributes permit semantics that are <span class="RFC">not
            required</span> of all Reading Systems. For example, some devices could be monochrome,
            or provide mainly audio or tactile interfaces. In such cases this specification
            generally <span class="RFC">requires</span> Reading Systems to accept all syntax (such
            as attribute values) permitted for the Preferred Vocabulary, but does <span class=
            "RFC">not require</span> that they be honored. For example, a Reading System
            <span class="RFC">must</span> parse and recognize the <span class=
            "Attribute">border</span> attribute on <span class="Element">table</span> elements, but
            <span class="RFC">may</span> choose to treat all values other than <span class=
            "AttributeValue">0</span> the same as <span class="AttributeValue">1</span>.
          </p>

          <p class="Copy">
            Note that this specification does not mandate specific rendering behavior for the OPS
            Preferred Vocabularies. Some Reading Systems could choose to express the intent of
            elements in presentation by closely following web browser usage — a blank line before a
            paragraph, but no first-line text-indent, for example. Other Reading Systems could gear
            their presentation towards sustained novel-like readability: for example, no extra
            whitespace between paragraphs, but text-indent on the first line of each. Still other
            systems, such as speech generators, could present particular elements or entire
            documents in completely different ways.
          </p>
        </div>
      </div>

      <div class="Section">
        <h1 class="SectionTitle">
          <a class="SectionTitle"
              href="#TOC3.0"
              id="Section3.0"
              name="Section3.0">3.0: OPS Style Sheets</a>
        </h1>

        <p class="Copy">
          Like CSS style sheets, OPS style sheets are case-insensitive, except for the parts that
          are not under the control of CSS. In particular, OPS Content Documents are XML documents
          and, as such, their element names and attribute values are case-sensitive. Therefore,
          corresponding element names and attribute values in OPS style sheets are case-sensitive.
          Currently, this applies only to element names, attribute names and attribute values used
          in selectors.
        </p>

        <p class="Copy">
          Where there are differences in the syntax specified by CSS1 and CSS2, OPS style sheets
          follow the CSS2 syntax. A list of these differences can be found in <a href=
          "http://www.w3.org/TR/REC-CSS2/grammar.html#tokenizer-diffs"
             target="_blank"
             title="Section D3 of the CSS2 specification.">section D3</a> of the W3C Recommendation
             REC-CSS2-19980512, "Cascading Style Sheets, level 2 (CSS2) Specification." OPS style
             sheets support the CSS construct of multiple declarations separated by semi-colons.
             Hence, the style sheet rules:
        </p>

        <pre class="Example">
h1 { color: blue }
h1 { font-weight: bold }
h1 { font-size: 12pt }
</pre>are equivalent to:

        <pre class="Example">
h1 { color: blue;
     font-weight: bold;
     font-size: 12pt }
</pre>
        <p class="Copy">
          Multiple rules with identical declaration blocks can be combined into one rule by
          separating the selectors with commas. Thus the rules:
        </p>

        <pre class="Example">
h1 {text-indent: 0em}
h2 {text-indent: 0em}
h3 {text-indent: 0em}
</pre>could be combined into the equivalent form:

        <pre class="Example">
h1, h2, h3 {text-indent: 0em}
</pre>
        <p class="Copy">
          OPS style sheets support all CSS white space characters. Specifically, the characters
          "space" (Unicode code 32), "tab" (9), "line feed" (10), "carriage return" (13), and "form
          feed" (12) can occur as whitespace. Comments of the syntax defined in the CSS2
          specification may be used in OPS-conforming CSS style sheets.
        </p>

        <p class="Copy">
          This specification supports the inline <span class="Attribute">style</span> attribute
          (deprecated), the XHTML <span class="Element">style</span> element, and externally linked
          (via <span class="Element">link</span> elements or the <span class=
          "Element">xml-stylesheet</span> processing instruction) style sheets. <ins>In DTBook, CSS
          style sheets can be included via the <span class="Element">xml-stylesheet</span>
          processing instruction. Thus, CSS styling can be applied to documents of both the XHTML
          and DTBook Preferred Vocabularies.</ins>
        </p>

        <p class="Copy">
          This specification assumes the use of selectors to be consistent with the definitions in
          the CSS2 Specification (see <a href="http://www.w3.org/TR/REC-CSS2/selector.html"
             target="_blank"
             title="CSS2 selectors.">http://www.w3.org/TR/REC-CSS2/selector.html</a> for details).
             For example, the rules for determining which of multiple rules are applied from a
             document’s style sheet are determined by the rules of inheritance, cascading and
             selector specificity (see <a href="http://www.w3.org/TR/CSS2/cascade.html"
             target="_blank"
             title="CSS2 cascading rules.">http://www.w3.org/TR/CSS2/cascade.html</a> for details).
        </p>

        <p class="Copy">
          If no style sheet is defined or no applicable style is found for a given <ins>XHTML</ins>
          OPS element, XHTML rendering is the default as defined elsewhere in this specification
          and the XHTML 1.1 specification.
        </p>

        <p class="Copy">
          This specification does <span class="RFC">not require</span> that Reading Systems
          implement text-to-speech or other read-aloud technology. Reading Systems that do not
          implement such technology <span class="RFC">may</span> ignore any CSS properties listed
          in this specification under the classification "aural style sheets," as well as the
          <span class="CSSProperty">speak-header</span> property listed under "Tables."
        </p>

        <p class="Copy">
          All properties apply to elements as defined in CSS. That is, most properties can apply to
          all elements, while a few are limited based on the value of the <span class=
          "CSSProperty">display</span> property (for example, <span class=
          "CSSProperty">text-align</span> only applies when the display type is <span class=
          "CSSPropertyValue">block</span>, not <span class="CSSPropertyValue">inline</span>).
          Reading Systems are, however, <span class="RFC">not required</span> to support every
          distinction; for example they <span class="RFC">may</span> choose to map a specific
          length value for <span class="CSSProperty">border-width</span> to one of the named values
          for that property.
        </p>

        <div class="Section">
          <h2 class="SubsectionTitle">
            <a class="SectionTitle"
                href="#TOC3.1"
                id="Section3.1"
                name="Section3.1">3.1: Selectors</a>
          </h2>

          <p class="Copy">
            Selectors specify the patterns that <span class="RFC">must</span> be matched in the
            target document to determine the elements to which the style declaration(s) in the
            accompanying declaration block apply. If all conditions in the pattern are true for a
            certain element, the selector matches the element and the declarations in the
            declaration block are applied. This specification assumes a use of selectors that is
            consistent with the CSS2 Specification. Reading Systems <span class="RFC">must</span>
            support all CSS2 selectors.
          </p>
        </div>

        <div class="Section">
          <h2 class="SubsectionTitle">
            <a class="SectionTitle"
                href="#TOC3.2"
                id="Section3.2"
                name="Section3.2">3.2: Value Types</a>
          </h2>

          <div class="Section">
            <h3 class="SubsubsectionTitle">
              <a class="SectionTitle"
                  href="#TOC3.2.1"
                  id="Section3.2.1"
                  name="Section3.2.1">3.2.1: URI Values</a>
            </h3>

            <p class="Copy">
              For those properties that take a URI value, the URI <span class="RFC">must</span>
              point to a document of appropriate media type for the property in question. All such
              referenced documents <span class="RFC">must</span> be contained within the OPF
              Package Document’s manifest.
            </p>
          </div>

          <div class="Section">
            <h3 class="SubsubsectionTitle">
              <a class="SectionTitle"
                  href="#TOC3.2.2"
                  id="Section3.2.2"
                  name="Section3.2.2">3.2.2: Integers and Real Numbers</a>
            </h3>

            <p class="Copy">
              Real numbers are denoted by <span class="Emphasis">number</span>, integer values by
              <span class="Emphasis">integer</span>. Either could have an <span class=
              "RFC">optional</span> sign value (one of "+" or "-"), though particular properties
              could restrict the ranges and sign of numeric values.
            </p>
          </div>

          <div class="Section">
            <h3 class="SubsubsectionTitle">
              <a class="SectionTitle"
                  href="#TOC3.2.3"
                  id="Section3.2.3"
                  name="Section3.2.3">3.2.3: Length</a>
            </h3>

            <p class="Copy">
              All non-zero coordinate and size values <span class="Emphasis">must</span> have
              specified units. All units defined by CSS1 and CSS2 are supported:
            </p>

            <table summary="CSS Units">
              <tr>
                <td>
                  px
                </td>
                <td>
                  Pixels
                </td>
              </tr>

              <tr>
                <td>
                  ex
                </td>
                <td>
                  x-height of current font
                </td>
              </tr>

              <tr>
                <td>
                  em
                </td>
                <td>
                  font-size of current font
                </td>
              </tr>

              <tr>
                <td>
                  pt
                </td>
                <td>
                  Points
                </td>
              </tr>

              <tr>
                <td>
                  in
                </td>
                <td>
                  Inches
                </td>
              </tr>

              <tr>
                <td>
                  cm
                </td>
                <td>
                  Centimeters
                </td>
              </tr>

              <tr>
                <td>
                  mm
                </td>
                <td>
                  Millimeters
                </td>
              </tr>

              <tr>
                <td>
                  pc
                </td>
                <td>
                  Picas
                </td>
              </tr>
            </table>
          </div>

          <div class="Section">
            <h3 class="SubsubsectionTitle">
              <a class="SectionTitle"
                  href="#TOC3.2.4"
                  id="Section3.2.4"
                  name="Section3.2.4">3.2.4: Percentages</a>
            </h3>

            <p class="Copy">
              Where percentage units are supported, they are used as defined for each property in
              the CSS specifications for which they are an allowed value.
            </p>
          </div>

          <div class="Section">
            <h3 class="SubsubsectionTitle">
              <a class="SectionTitle"
                  href="#TOC3.2.5"
                  id="Section3.2.5"
                  name="Section3.2.5">3.2.5: Color</a>
            </h3>

            <p class="Copy">
              Current browsers support a host of keyword color names. XHTML 1.1 defines 16 named
              colors, as well as numeric values. OPS style sheets <span class="RFC">may</span> use
              all CSS2 forms, however Reading Systems are <span class="RFC">not required</span> to
              distinguish all these colors for rendering (otherwise monochrome devices would
              necessarily be non-conforming, which is not the intent).
            </p>

            <table summary="CSS Colors">
              <tr>
                <td>
                  Black
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td>
                  White
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td>
                  Aqua
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td>
                  Blue
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td>
                  Fuschia
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td>
                  Gray
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td>
                  Green
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td>
                  Lime
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td>
                  Maroon
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td>
                  Navy
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td>
                  Olive
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td>
                  Purple
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td>
                  Red
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td>
                  Silver
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td>
                  Teal
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td>
                  Yellow
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td>
                  #rrggbb
                </td>
                <td>
                  six-digit hexadecimal
                </td>
              </tr>

              <tr>
                <td>
                  #rgb
                </td>
                <td>
                  three-digit hexadecimal
                </td>
              </tr>

              <tr>
                <td>
                  rgb(r, g, b)
                </td>
                <td>
                  integers in the range 0-255
                </td>
              </tr>

              <tr>
                <td>
                  rgb(r%, g%, b%)
                </td>
                <td>
                  floats in the range of 0.0% to 100.0%
                </td>
              </tr>
            </table>
          </div>

          <div class="Section">
            <h3 class="SubsubsectionTitle">
              <a class="SectionTitle"
                  href="#TOC3.2.6"
                  id="Section3.2.6"
                  name="Section3.2.6">3.2.6: Time</a>
            </h3>

            <p class="Copy">
              Units defined by CSS2 are supported:
            </p>

            <table summary="CSS Time Units">
              <tr>
                <td>
                  s
                </td>
                <td>
                  Seconds
                </td>
              </tr>

              <tr>
                <td>
                  ms
                </td>
                <td>
                  Milliseconds
                </td>
              </tr>
            </table>
          </div>

          <div class="Section">
            <h3 class="SubsubsectionTitle">
              <a class="SectionTitle"
                  href="#TOC3.2.7"
                  id="Section3.2.7"
                  name="Section3.2.7">3.2.7: Frequency</a>
            </h3>

            <p class="Copy">
              Units defined by CSS2 are supported:
            </p>

            <table summary="CSS Frequencies">
              <tr>
                <td>
                  Hz
                </td>
                <td>
                  Hertz
                </td>
              </tr>

              <tr>
                <td>
                  kHz
                </td>
                <td>
                  Kilohertz
                </td>
              </tr>
            </table>
          </div>

          <div class="Section">
            <h3 class="SubsubsectionTitle">
              <a class="SectionTitle"
                  href="#TOC3.2.8"
                  id="Section3.2.8"
                  name="Section3.2.8">3.2.8: Strings</a>
            </h3>

            <p class="Copy">
              Strings <span class="RFC">must</span> be quoted using either single or double quotes
              (Unicode codes 39 or 34, respectively). Nested strings <span class="RFC">must</span>
              be escaped with a backslash (e.g. " a \"nested\" string"). To embed a line break in a
              string, use the escape "\A". The hexadecimal "A" is the line feed character in
              Unicode, but represents the generic notion of "newline" in CSS.
            </p>
          </div>
        </div>

        <div class="Section">
          <h2 class="SubsectionTitle">
            <a class="SectionTitle"
                href="#TOC3.3"
                id="Section3.3"
                name="Section3.3">3.3: Properties</a>
          </h2>

          <p class="Copy">
            Default values for all supported CSS properties are as listed in CSS2.
          </p>

          <p class="Copy">
            The following table lists all CSS properties and values supported by this
            specification. Where not all values given in the CSS2 specification are listed for a
            given property, those values not listed are not supported by this specification. The
            column “Alternate display” indicates acceptable fallback display for CSS values that a
            Reading System cannot display as intended.
          </p>

          <p class="Copy">
            Properties that are unique to this specification have been <span class=
            "Underline">underlined</span>.
          </p>

          <table summary="Supported CSS Properties">
            <thead>
              <tr>
                <td class="header">
                  CSS Structure
                </td>
                <td class="header">
                  Alternate Display
                </td>
                <td class="header">
                  CSS2 Section
                </td>
              </tr>
            </thead>

            <tbody>
              <tr>
                <td class="subheader">
                  Media Types
                </td>
                <td>
                </td>
                <td>
                  7
                </td>
              </tr>

              <tr>
                <td class="property">
                  @media
                </td>
                <td>
                </td>
                <td>
                  7.2.1
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  aural
                </td>
                <td>
                </td>
                <td>
                  7.3
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  all
                </td>
                <td>
                </td>
                <td>
                  7.3
                </td>
              </tr>

              <tr>
                <td class="subheader">
                  Page Model
                </td>
                <td>
                </td>
                <td>
                  13.2
                </td>
              </tr>

              <tr>
                <td class="property">
                  @page
                </td>
                <td>
                </td>
                <td>
                  13.2
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  :left
                </td>
                <td>
                </td>
                <td>
                  13.2.4
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  :right
                </td>
                <td>
                </td>
                <td>
                  13.2.4
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  :first
                </td>
                <td>
                </td>
                <td>
                  13.2.4
                </td>
              </tr>

              <tr>
                <td class="subheader">
                  Box Model
                </td>
                <td>
                </td>
                <td>
                  8
                </td>
              </tr>

              <tr>
                <td class="subsubheader">
                  Margins
                </td>
                <td>
                </td>
                <td>
                  8.3
                </td>
              </tr>

              <tr>
                <td class="property">
                  margin-top, margin-bottom, margin-left, margin-right
                </td>
                <td>
                </td>
                <td>
                  8.3
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  &lt;length&gt;
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  &lt;percentage&gt;
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  margin [2]
                </td>
                <td>
                </td>
                <td>
                  8.3
                </td>
              </tr>

              <tr>
                <td class="property">
                  auto
                </td>
                <td class="propertyvalue2">
                  0 [1]
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="subheader">
                  Padding
                </td>
                <td>
                </td>
                <td>
                  8.4
                </td>
              </tr>

              <tr>
                <td class="property">
                  padding-top, padding-bottom, padding-left, padding-right
                </td>
                <td>
                </td>
                <td>
                  8.4
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  &lt;length&gt;
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  &lt;percentage&gt;
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  padding [2]
                </td>
                <td>
                </td>
                <td>
                  8.4
                </td>
              </tr>

              <tr>
                <td class="subheader">
                  Borders
                </td>
                <td>
                </td>
                <td>
                  8.5
                </td>
              </tr>

              <tr>
                <td class="property">
                  border-top-width, border-bottom-width, border-left-width, border-right-width
                </td>
                <td>
                </td>
                <td>
                  8.5.1
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  thin
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  medium
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  thick
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  &lt;length&gt;
                </td>
                <td class="propertyvalue2">
                  thin/medium/thick [3]
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  border-width [2]
                </td>
                <td class="propertyvalue2">
                  thin/medium/thick [3]
                </td>
                <td>
                  8.5.1
                </td>
              </tr>

              <tr>
                <td class="property">
                  border-top-color, border-bottom-color, border-left-color, border-right-color
                </td>
                <td>
                </td>
                <td>
                  8.5.2
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  &lt;color&gt;
                </td>
                <td>
                  [4]
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  transparent
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  border-color [2]
                </td>
                <td>
                </td>
                <td>
                  8.5.2
                </td>
              </tr>

              <tr>
                <td class="property">
                  border-top-style, border-bottom-style, border-left-style, border-right-style
                </td>
                <td>
                </td>
                <td>
                  8.5.3
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  none
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  hidden
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  dotted
                </td>
                <td class="propertyvalue2">
                  solid
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  dashed
                </td>
                <td class="propertyvalue2">
                  solid
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  solid
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  double
                </td>
                <td class="propertyvalue2">
                  solid
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  groove
                </td>
                <td class="propertyvalue2">
                  solid
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  ridge
                </td>
                <td class="propertyvalue2">
                  solid
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inset
                </td>
                <td class="propertyvalue2">
                  solid
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  outset
                </td>
                <td class="propertyvalue2">
                  solid
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  border-style [2]
                </td>
                <td>
                </td>
                <td>
                  8.5.3
                </td>
              </tr>

              <tr>
                <td class="property">
                  border-top, border-bottom, border-left, border-right [2]
                </td>
                <td>
                </td>
                <td>
                  8.5.4
                </td>
              </tr>

              <tr>
                <td class="property">
                  border [2]
                </td>
                <td>
                </td>
                <td>
                  8.5.4
                </td>
              </tr>

              <tr>
                <td class="subheader">
                  Visual Display Model
                </td>
                <td>
                </td>
                <td>
                  9
                </td>
              </tr>

              <tr>
                <td class="property">
                  display [5]
                </td>
                <td>
                </td>
                <td>
                  9.2.5
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  none
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inline
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  block
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  run-in
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  table
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inline-table
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  table-row-group
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  table-header-group
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  table-footer-group
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  table-column-group
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  table-row
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  table-column
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  table-cell
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  table-caption
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  <span class="Underline">oeb-page-head</span> [6]
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  <span class="Underline">oeb-page-foot</span> [6]
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  float
                </td>
                <td>
                </td>
                <td>
                  9.5.1
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  left
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  right
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  none
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  clear
                </td>
                <td>
                </td>
                <td>
                  9.5.2
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  none
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  left
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  right
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  both
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  direction
                </td>
                <td>
                </td>
                <td>
                  9.1
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  ltr
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  rtl
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  unicode-bidi
                </td>
                <td>
                </td>
                <td>
                  9.1
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  normal
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  embed
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  bidi-override
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  <span class="Underline">oeb-column-number</span> [13]
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  auto
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  &lt;integer&gt;
                </td>
                <td class="propertyvalue2">
                  1
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="subheader">
                  Visual Formatting Model Details
                </td>
                <td>
                </td>
                <td>
                  10
                </td>
              </tr>

              <tr>
                <td class="property">
                  width
                </td>
                <td>
                </td>
                <td>
                  10.2
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  &lt;length&gt;
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  &lt;percentage&gt;
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  auto
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  min-width
                </td>
                <td>
                </td>
                <td>
                  10.4
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  &lt;length&gt;
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  &lt;percentage&gt;
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  max-width
                </td>
                <td>
                </td>
                <td>
                  10.4
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  &lt;length&gt;
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  &lt;percentage&gt;
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  auto
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  height
                </td>
                <td>
                </td>
                <td>
                  10.5
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  &lt;length&gt;
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  &lt;percentage&gt;
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  auto
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  min-height
                </td>
                <td>
                </td>
                <td>
                  10.7
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  &lt;length&gt;
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  &lt;percentage&gt;
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  max-height
                </td>
                <td>
                </td>
                <td>
                  10.7
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  &lt;length&gt;
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  &lt;percentage&gt;
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  none
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  line-height
                </td>
                <td>
                </td>
                <td>
                  10.8.1
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  normal
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  &lt;number&gt;
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  &lt;length&gt;
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  &lt;percentage&gt;
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  vertical-align
                </td>
                <td>
                </td>
                <td>
                  10.8.1
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  baseline
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  sub
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  super
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  top
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  text-top
                </td>
                <td>
                  [7]
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  middle
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  bottom
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  ext-bottom
                </td>
                <td>
                  [8]
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="subheader">
                  Generated Content, Automatic Numbering, and Lists
                </td>
                <td>
                </td>
                <td>
                  12
                </td>
              </tr>

              <tr>
                <td class="property">
                  content [9]
                </td>
                <td>
                </td>
                <td>
                  12.2
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  &lt;string&gt;
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  list-style-type
                </td>
                <td>
                </td>
                <td>
                  12.6.2
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  none
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  disc
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  circle
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  square
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  decimal
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  decimal-leading-zero
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  lower-roman
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  upper-roman
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  lower-greek
                </td>
                <td>
                  Decimal
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  upper-greek
                </td>
                <td>
                  Decimal
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  lower-alpha
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  lower-latin
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  upper-alpha
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  upper-latin
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  hebrew
                </td>
                <td>
                  Decimal
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  armenian
                </td>
                <td>
                  Decimal
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  georgian
                </td>
                <td>
                  Decimal
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  cjk-ideographic
                </td>
                <td>
                  Decimal
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  hiragana
                </td>
                <td>
                  Decimal
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  katakana
                </td>
                <td>
                  Decimal
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  hiragana-iroha
                </td>
                <td>
                  Decimal
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  katakana-iroha
                </td>
                <td>
                  Decimal
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  list-style-position
                </td>
                <td>
                </td>
                <td>
                  12.6.2
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inside
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  outside
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  list-style [2]
                </td>
                <td>
                </td>
                <td>
                  12.6.2
                </td>
              </tr>

              <tr>
                <td class="subheader">
                  Paged Media
                </td>
                <td>
                </td>
                <td>
                  13
                </td>
              </tr>

              <tr>
                <td class="property">
                  page-break-before
                </td>
                <td>
                </td>
                <td>
                  13.3.1
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  auto
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  always
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  avoid
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  left
                </td>
                <td>
                  [10]
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  right
                </td>
                <td>
                  [10]
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  page-break-after
                </td>
                <td>
                </td>
                <td>
                  13.3.1
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  auto
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  always
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  avoid
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  left
                </td>
                <td>
                  [10]
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  right
                </td>
                <td>
                  [10]
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  page-break-inside
                </td>
                <td>
                </td>
                <td>
                  13.3.1
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  auto
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  avoid
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  orphans
                </td>
                <td>
                </td>
                <td>
                  13.3.3
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  &lt;integer&gt;
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  widows
                </td>
                <td>
                </td>
                <td>
                  13.3.3
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  &lt;integer&gt;
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="subheader">
                  Colors and Backgrounds
                </td>
                <td>
                </td>
                <td>
                  14
                </td>
              </tr>

              <tr>
                <td class="property">
                  color
                </td>
                <td>
                </td>
                <td>
                  14.1
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  &lt;color&gt;
                </td>
                <td>
                  [4]
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  background-color
                </td>
                <td>
                </td>
                <td>
                  14.2.1
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  &lt;color&gt;
                </td>
                <td>
                  [4]
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  transparent
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="subheader">
                  Fonts
                </td>
                <td>
                </td>
                <td>
                  15
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  font-family
                </td>
                <td>
                </td>
                <td>
                  15.2.2
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  &lt;family-name&gt;
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  sans-serif
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  serif
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  monospace
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  font-style
                </td>
                <td>
                </td>
                <td>
                  15.2.3
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  normal
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  italic
                </td>
                <td>
                  [11]
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  oblique
                </td>
                <td>
                  [11]
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  font-variant
                </td>
                <td>
                </td>
                <td>
                  15.2.3
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  normal
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  small-caps
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  font-weight
                </td>
                <td>
                </td>
                <td>
                  15.2.3
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  normal
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  bold
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  100-900
                </td>
                <td>
                  [3]
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  font-size
                </td>
                <td>
                </td>
                <td>
                  15.2.4
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  xx-small
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  x-small
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  small
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  medium
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  large
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  x-large
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  xx-large
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  smaller
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  larger
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  &lt;length&gt;
                </td>
                <td>
                  [3]
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  &lt;percentage&gt;
                </td>
                <td>
                  [3]
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  font [2]
                </td>
                <td>
                </td>
                <td>
                  15.2.5
                </td>
              </tr>

              <tr>
                <td class="subheader">
                  Text
                </td>
                <td>
                </td>
                <td>
                  16
                </td>
              </tr>

              <tr>
                <td class="property">
                  text-indent
                </td>
                <td>
                </td>
                <td>
                  16.1
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  &lt;length&gt;
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  &lt;percentage&gt;
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  text-align
                </td>
                <td>
                </td>
                <td>
                  16.2
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  left
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  right
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  center
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  justify
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  text-decoration
                </td>
                <td>
                </td>
                <td>
                  16.3.1
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  none
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  line-through
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  underline
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  white-space
                </td>
                <td>
                </td>
                <td>
                  16.6
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  normal
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  pre
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  nowrap
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="subheader">
                  Tables
                </td>
                <td>
                </td>
                <td>
                  17
                </td>
              </tr>

              <tr>
                <td class="property">
                  caption-side
                </td>
                <td>
                </td>
                <td>
                  17.4.1
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  top
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  bottom
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  left
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  right
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  table-layout
                </td>
                <td>
                </td>
                <td>
                  17.5.2
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  fixed
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  auto
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  speak-header
                </td>
                <td>
                </td>
                <td>
                  17.7.1
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  once
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  always
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="subheader">
                  Aural Style Sheets
                </td>
                <td>
                </td>
                <td>
                  19
                </td>
              </tr>

              <tr>
                <td class="property">
                  volume
                </td>
                <td>
                </td>
                <td>
                  19.2
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  silent
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  x-soft
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  soft
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  medium
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  loud
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  x-loud
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  &lt;percentage&gt;
                </td>
                <td>
                  [3]
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  0–100
                </td>
                <td>
                  [3]
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  speak
                </td>
                <td>
                </td>
                <td>
                  19.3
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  normal
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  none
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  spell-out
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  pause-before
                </td>
                <td>
                </td>
                <td>
                  19.4
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  &lt;time&gt;
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  &lt;percentage&gt;
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  pause-after
                </td>
                <td>
                </td>
                <td>
                  19.4
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  &lt;time&gt;
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  &lt;percentage&gt;
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  pause [2]
                </td>
                <td>
                </td>
                <td>
                  19.4
                </td>
              </tr>

              <tr>
                <td class="property">
                  cue-before
                </td>
                <td>
                </td>
                <td>
                  19.5
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  &lt;uri&gt;
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  none
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  cue-after
                </td>
                <td>
                </td>
                <td>
                  19.5
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  &lt;uri&gt;
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  none
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  cue [2]
                </td>
                <td>
                </td>
                <td>
                  19.5
                </td>
              </tr>

              <tr>
                <td class="property">
                  speech-rate
                </td>
                <td>
                </td>
                <td>
                  19.8
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  x-slow
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  slow
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  medium
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  fast
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  x-fast
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  faster
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  slower
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  &lt;number&gt; [12]
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  voice-family
                </td>
                <td>
                </td>
                <td>
                  19.8
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  male
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  female
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  child
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  pitch
                </td>
                <td>
                </td>
                <td>
                  19.8
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  x-low
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  low
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  medium
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  high
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  x-high
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  &lt;frequency&gt;
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  stress
                </td>
                <td>
                </td>
                <td>
                  19.8
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  0-100
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  richness
                </td>
                <td>
                </td>
                <td>
                  19.8
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  0-100
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  speak-punctuation
                </td>
                <td>
                </td>
                <td>
                  19.9
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  code
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  none
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="property">
                  speak-numeral
                </td>
                <td>
                </td>
                <td>
                  19.9
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  digits
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  continuous
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>

              <tr>
                <td class="propertyvalue">
                  inherit
                </td>
                <td>
                </td>
                <td>
                </td>
              </tr>
            </tbody>
          </table>

          <p class="Copy">
            [1] Reading Systems <span class="RFC">may</span> set the value of any <span class=
            "CSSProperty">margin</span> property whose specified value is <span class=
            "CSSPropertyValue">auto</span> to <span class="CSSPropertyValue">0</span>.
          </p>

          <p class="Copy">
            [2] This is a shorthand property. The syntax for its value is given in the CSS2
            specification. Where this specification limits values or indicates alternate
            representations for properties abbreviated by this property, the same limits and
            alternate representations apply to this property.
          </p>

          <p class="Copy">
            [3] Reading Systems <span class="RFC">may</span> map to one of the keyword values
            listed for this property.
          </p>

          <p class="Copy">
            [4] See <a href="#Section3.2.5"
               title="Section 3.2.5">Section 3.2.5</a> on color units.
          </p>

          <p class="Copy">
            [5] CSS2 provides a full description of the various table values and their correct
            renderings. Please refer to the CSS2 Tables specification (<a href=
            "http://www.w3.org/TR/REC-CSS2/tables.html"
               target="_blank"
               title="CSS2 tables specification.">http://www.w3.org/TR/REC-CSS2/tables.html</a>)
               for a more detailed discussion of the various table values.
          </p>

          <p class="Copy">
            CSS2 and XHTML provide similar but subtly different algorithms for rendering table
            data. These algorithms tend to generate the same results, but there are a few
            exceptions. In such cases, conforming Reading Systems <span class="RFC">must</span>
            produce output consistent with the algorithm specified by CSS2.
          </p>

          <p class="Copy">
            When using tables, authors <span class="RFC">should</span> follow the Techniques for
            Web Accessibility Guidelines (<a href="http://www.w3.org/TR/WAI-WEBCONTENT-TECHS/"
               target="_blank"
               title="WAI Guidelines.">http://www.w3.org/TR/WAI-WEBCONTENT-TECHS/</a>) for
               maintaining as much semantic information as possible. That document describes good
               practices for choosing how and when to use table tags, and when to use CSS
               properties. Specifically, see "Guideline 5: Create tables that transform gracefully"
               (<a href="http://www.w3.org/TR/WAI-WEBCONTENT-TECHS/#gl-table-markup"
               target="_blank"
               title=
               "WAI Guideline 5.">http://www.w3.org/TR/WAI-WEBCONTENT-TECHS/#gl-table-markup</a>).
          </p>

          <p class="Copy">
            [6] The content of an element assigned <span class="CSSProperty">display:</span>
            <span class="CSSPropertyValue">oeb-page-head</span> <span class="RFC">should</span> be
            presented only as a header, and the content of an element assigned <span class=
            "CSSProperty">display:</span> <span class="CSSPropertyValue">oeb-page-foot</span>
            <span class="RFC">should</span> be presented only as a footer. Neither <span class=
            "RFC">should</span> be simply presented as if it were inline or block. Reading Systems,
            however, are free to present headers and footers either in special areas as usual for
            paper publications, or to make them available in another way. For example, a device
            with a small screen might instead pop them up on demand. For purposes of page layout,
            these display values are similar to block boxes with an absolute position (i.e. a
            <span class="CSSProperty">position</span> value of <span class=
            "CSSPropertyValue">fixed</span> or <span class="CSSPropertyValue">absolute</span>).
            That is, they are removed from the normal flow and a new block box is created with its
            own flow. Margins, padding and other block characteristics are determined as if the
            element had <span class="CSSProperty">position:</span> <span class=
            "CSSPropertyValue">fixed</span> set.
          </p>

          <p class="Copy">
            An element assigned <span class="CSSProperty">display:</span> <span class=
            "CSSPropertyValue">oeb-page-head</span> or <span class="CSSProperty">display:</span>
            <span class="CSSPropertyValue">oeb-page-foot</span> <span class="RFC">shall not</span>
            be considered in effect while any preceding content remains presented. For example,
            when rendered to a screen with appropriate style settings, the <span class=
            "AttributeValue">myhead</span>-classed <span class="Element">div</span> element below
            would become the page header as soon as nothing preceding the containing <span class=
            "Element">div</span> is displayed:
          </p>

          <pre class="Example">
&lt;div&gt;
   &lt;div class="myhead" style="display: oeb-page-head"&gt;
      The OEB Publication Structure: Introduction
   &lt;/div&gt;
   &lt;h2&gt;Introduction&lt;/h2&gt;
   &lt;p&gt;...&lt;/p&gt;
&lt;/div&gt;
</pre>
          <p class="Copy">
            Such a header (or footer) remains in effect until another header (or footer) is in
            effect instead, or until no part of its parent element remains presented (such as when
            the <span class="Element">div</span> is no longer visible in the above example),
            whichever occurs first.
          </p>

          <p class="Copy">
            [7] Reading System <span class="RFC">may</span> map to top.
          </p>

          <p class="Copy">
            [8] Reading System <span class="RFC">may</span> map to bottom.
          </p>

          <p class="Copy">
            [9] <span class="RFC">Must not</span> be used within a style sheet whose <span class=
            "CSSProperty">@media</span> value is other than <span class=
            "CSSPropertyValue">aural</span>.
          </p>

          <p class="Copy">
            [10] One-page Reading Systems <span class="RFC">must</span> treat <span class=
            "CSSPropertyValue">left</span> and <span class="CSSPropertyValue">right</span> as
            <span class="CSSPropertyValue">always</span>.
          </p>

          <p class="Copy">
            [11] Reading Systems <span class="RFC">need not</span> distinguish <span class=
            "CSSPropertyValue">italic</span> and <span class="CSSPropertyValue">oblique</span> from
            each other.
          </p>

          <p class="Copy">
            [12] Number specifies the speaking rate in words per minute.
          </p>

          <p class="Copy">
            [13] Specifies a number of columns in which to render content; <span class=
            "RFC">may</span> be applied to all block level elements. Reading Systems are free to
            support integer values other than <span class="CSSPropertyValue">1</span>, or
            <span class="RFC">may</span> map them to <span class="CSSPropertyValue">1</span>.
            Reading Systems may support column balancing. A value of <span class=
            "CSSPropertyValue">auto</span> allows the Reading System to decide on the optimal
            number of columns in which to render content, considering available width, font sizes,
            or any other metrics it considers relevant for readability.
          </p>
        </div>

        <div class="Section">
          <h2 class="SubsectionTitle">
            <a class="SectionTitle"
                href="#TOC3.4"
                id="Section3.4"
                name="Section3.4">3.4: Embedded Fonts</a>
          </h2>

          <p class="Copy">
            To provide authors with control over the appearance of the text, OPS supports the CSS2
            font-face at-rule (@font-face). See <a href=
            "http://www.w3.org/TR/1998/REC-CSS2-19980512/fonts.html#font-selection"
               target="_blank"
               title="CSS2 - Font Selection">section 15.3.1</a> of the CSS2 Recommendation. The
               following font descriptors <span class="RFC">must</span> be supported:
          </p>

          <ul>
            <li>
              <span class="CSSProperty">font-family</span>
            </li>

            <li>
              <span class="CSSProperty">font-style</span>
            </li>

            <li>
              <span class="CSSProperty">font-variant</span>
            </li>

            <li>
              <span class="CSSProperty">font-weight</span>
            </li>

            <li>
              <span class="CSSProperty">font-size</span>
            </li>

            <li>
              <span class="CSSProperty">src</span>
            </li>
          </ul>

          <p class="Copy">
            For portability, authors <span class="RFC">must not</span> use any other descriptors.
            Font files <span class="RFC">must</span> carry all information needed for rendering
            Unicode characters. Fonts <span class="RFC">must not</span> provide mappings for
            Unicode characters that would change the semantics of the text (e.g. mapping the letter
            "A" to a biohazard symbol). Content creators <span class="RFC">must not</span> assume
            that any particular font format is supported. Fonts could be included in multiple
            formats by using a list of files for the <span class="CSSProperty">src</span>
            descriptor; the first supported format <span class="RFC">should</span> be used. At
            least one file in OpenType format <span class="RFC">should</span> always be included in
            the list. It is advisable for a Reading System to support the OpenType font format, but
            this is not a conformance requirement; a reading system <span class="RFC">may</span>
            support no embedded font formats at all. Content creators <span class=
            "RFC">should</span> use comma-separated lists for font-family properties to specify
            fallback font choices.
          </p>

          <p class="Copy">
            Content creators <span class="RFC">must</span> always honor usage restrictions that are
            encoded in OpenType fonts (and many other font formats). Fonts that are marked "no
            embedding" <span class="RFC">must not</span> be included in OPS Publications.
          </p>

          <p class="Copy">
            <ins>Any font files included in an OPS Publication <span class="RFC">must</span> be
            included in the OPF <span class="Element">manifest</span> with appropriate media
            type.</ins>
          </p>
        </div>
      </div>
    </div>

    <div class="BackMatter">
      <h1 class="AppendixTitle">
        Appendices
      </h1>

      <div class="Section">
        <h2 class="SectionTitle">
          <a class="SectionTitle"
              href="#AppendixTOCA"
              id="AppendixA"
              name="AppendixA">Appendix A: The NVDL Definition of OPS <ins>XHTML Content
              Documents</ins></a>
        </h2>

        <p class="Copy">
          This NVDL specification references three XML schemas:
        </p>

        <ol>
          <li>The XHTML DTD
          </li>

          <li>The SVG RelaxNG schema
          </li>

          <li>The OPS RelaxNG schema
          </li>
        </ol>

        <p class="Copy">
          The first two of these are referenced externally; the OPS schema is defined in <a href=
          "#AppendixB"
             title="The OPS Schema.">Appendix B</a>.
        </p>

        <pre class="Example">
&lt;?xml version="1.0" encoding="UTF-8"?&gt;
&lt;rules xmlns="http://purl.oclc.org/dsdl/nvdl/ns/structure/1.0"
       startMode="valid-ops" xmlns:html="http://www.w3.org/1999/xhtml"&gt;

&lt;!-- mode that allows any elements --&gt;
&lt;mode name="anything"&gt;
   &lt;anyNamespace&gt;
      &lt;allow/&gt;
   &lt;/anyNamespace&gt;
&lt;/mode&gt;

&lt;!-- mode that only allows either valid SVG fragment --&gt;
&lt;!-- or arbitrary XHTML fragment --&gt;
&lt;mode name="blessed-xhtml"&gt;
   &lt;namespace ns="http://www.w3.org/2000/svg"&gt;
      &lt;validate schema="http://www.w3.org/Graphics/SVG/1.1/rng/svg11.rng"
                useMode="svg-content"/&gt;
   &lt;/namespace&gt;
   &lt;namespace ns="http://www.w3.org/1999/xhtml"&gt;
      &lt;allow/&gt;
   &lt;/namespace&gt;
&lt;/mode&gt;

&lt;!-- mode that only allows arbitrary SVG fragment --&gt;
&lt;mode name="blessed-svg"&gt;
   &lt;namespace ns="http://www.w3.org/2000/svg"&gt;
      &lt;allow/&gt;
   &lt;/namespace&gt;
&lt;/mode&gt;

&lt;!-- mode that allows any elements --&gt;
&lt;!-- any XHTML fragments are attached in place of --&gt;
&lt;!-- the OPS fragment that invoked this mode --&gt;
&lt;mode name="xhtml-attach"&gt;
   &lt;namespace ns="http://www.w3.org/1999/xhtml"&gt;
      &lt;attach/&gt;
   &lt;/namespace&gt;
   &lt;anyNamespace&gt;
      &lt;allow/&gt;
   &lt;/anyNamespace&gt;
&lt;/mode&gt;

&lt;!-- mode that allows any elements --&gt;
&lt;!-- any SVG fragments are attached in place of the OPS fragment --&gt;
&lt;!-- that invoked this mode --&gt;
&lt;mode name="svg-attach"&gt;
   &lt;namespace ns="http://www.w3.org/2000/svg"&gt;
      &lt;attach/&gt;
   &lt;/namespace&gt;
   &lt;anyNamespace&gt;
      &lt;allow/&gt;
   &lt;/anyNamespace&gt;
&lt;/mode&gt;

&lt;!-- mode that allows any valid XHTML with SVG islands included --&gt;
&lt;!-- and OPS switch elements with valid default clause --&gt;
&lt;mode name="valid-ops"&gt;
   &lt;namespace ns="http://www.w3.org/1999/xhtml"&gt;
      &lt;validate schema="http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd"
                schemaType="application/xml-dtd" useMode="xhtml-content"/&gt;
   &lt;/namespace&gt;
&lt;/mode&gt;

&lt;!-- mode that validates SVG and OPS islands inside XHTML --&gt;
&lt;mode name="xhtml-content"&gt;
   &lt;namespace ns="http://www.w3.org/2000/svg"&gt;
      &lt;validate schema="http://www.w3.org/Graphics/SVG/1.1/rng/svg11.rng"
                useMode="svg-content"/&gt;
   &lt;/namespace&gt;
   &lt;namespace ns="http://www.w3.org/1999/xhtml"&gt;
      &lt;attach/&gt;
   &lt;/namespace&gt;
   &lt;namespace ns="http://www.idpf.org/2007/ops"&gt;
      &lt;!-- doing two independent thing here --&gt;
      &lt;!-- first, attach XHTML islands from default element into the XHTML --&gt;
      &lt;!-- tree so that they can be validated in the right context --&gt;
      &lt;unwrap useMode="xhtml-attach"&gt;
         &lt;context path="case" useMode="anything"/&gt;
      &lt;/unwrap&gt;
      &lt;!-- next, validate OPS itself (switch element), paying attention to --&gt;
      &lt;!-- what can go inside case and default elements --&gt;
      &lt;validate schema="ops20.rng"&gt;
         &lt;context path="case" useMode="anything"/&gt;
         &lt;context path="default" useMode="blessed-xhtml"/&gt;
      &lt;/validate&gt;
   &lt;/namespace&gt;
&lt;/mode&gt;

&lt;!-- mode that validates OPS islands inside SVG --&gt;
&lt;mode name="svg-content"&gt;
   &lt;namespace ns="http://www.w3.org/2000/svg"&gt;
      &lt;attach/&gt;
   &lt;/namespace&gt;
   &lt;namespace ns="http://www.idpf.org/2007/ops"&gt;
      &lt;!-- doing two independent thing here --&gt;
      &lt;!-- first, attach SVG islands from default element into SVG tree, --&gt;
      &lt;!-- so that they can be validated in the right context --&gt;
      &lt;unwrap useMode="svg-attach"&gt;
         &lt;context path="case" useMode="anything"/&gt;
      &lt;/unwrap&gt;
      &lt;!-- next, validate OPS itself (switch element), paying attention --&gt;
      &lt;!-- to what can go inside case and default elements --&gt;
      &lt;validate schema="ops20.rng"&gt;
         &lt;context path="case" useMode="anything"/&gt;
         &lt;context path="default" useMode="blessed-svg"/&gt;
      &lt;/validate&gt;
   &lt;/namespace&gt;
&lt;/mode&gt;
&lt;/rules&gt;
</pre>
      </div>

      <div class="Section">
        <h2 class="SectionTitle">
          <a class="SectionTitle"
              href="#AppendixTOCB"
              id="AppendixB"
              name="AppendixB">Appendix B: The OPS Schema</a>
        </h2>

        <p class="Copy">
          &nbsp;
        </p>

        <pre class="Example">
&lt;?xml version="1.0" encoding="UTF-8"?&gt;
&lt;grammar ns="http://www.idpf.org/2007/ops" xml:lang="en"
         xmlns="http://relaxng.org/ns/structure/1.0"
         datatypeLibrary="http://www.w3.org/2001/XMLSchema-datatypes"&gt;

&lt;start&gt;
   &lt;ref name="OPS.switch"/&gt;
&lt;/start&gt;

&lt;define name="OPS.switch"&gt;
   &lt;element name="switch"&gt;
      &lt;optional&gt;
         &lt;attribute name="id"&gt;
            &lt;data type="ID"/&gt;
         &lt;/attribute&gt;
      &lt;/optional&gt;
      &lt;oneOrMore&gt;
         &lt;element name="case"&gt;
            &lt;optional&gt;
               &lt;attribute name="id"&gt;
                  &lt;data type="ID"/&gt;
               &lt;/attribute&gt;
            &lt;/optional&gt;
            &lt;attribute name="required-namespace"&gt;
               &lt;text/&gt;
            &lt;/attribute&gt;
            &lt;optional&gt;
               &lt;attribute name="required-modules"&gt;
                  &lt;text/&gt;
               &lt;/attribute&gt;
            &lt;/optional&gt;
            &lt;zeroOrMore&gt;
               &lt;ref name="OPS.switch"/&gt;
            &lt;/zeroOrMore&gt;
         &lt;/element&gt;
      &lt;/oneOrMore&gt;
      &lt;element name="default"&gt;
         &lt;optional&gt;
            &lt;attribute name="id"&gt;
               &lt;data type="ID"/&gt;
            &lt;/attribute&gt;
         &lt;/optional&gt;
&lt;zeroOrMore&gt;
            &lt;ref name="OPS.switch"/&gt;
         &lt;/zeroOrMore&gt;
      &lt;/element&gt;
   &lt;/element&gt;
&lt;/define&gt;

&lt;/grammar&gt;
</pre>
      </div>

      <div class="Section">
        <h2 class="SectionTitle">
          <a class="SectionTitle"
              href="#AppendixTOCC"
              id="AppendixC"
              name="AppendixC">Appendix C: Contributors</a>
        </h2>

        <p class="Copy">
          This specification has been developed through a cooperative effort, bringing together
          publishers, Reading System vendors, software developers, and experts in the relevant
          standards.
        </p>

        <p class="Copy">
          Version 2.0 of this specification was prepared by the International Digital Publishing
          Forum (IDPF) Open eBook Publication Structure (OEBPS) Working Group. Members of the
          working group at the time of publication of revision 2.0 were:
        </p>

        <ul class="AuthorList">
          <li>Angel Ancin, iRex Technologies
          </li>

          <li>Rick Bowes, Thomson Learning
          </li>

          <li>Peter Brantley, Digital Library Federation
          </li>

          <li>Clint Brauer, SONY
          </li>

          <li>Ken Brooks, Thomson Learning
          </li>

          <li>Janice Carter, Benetech
          </li>

          <li>Richard Cohn, Adobe Systems, Inc.
          </li>

          <li>Garth Conboy, eBook Technologies, Inc. (Working Group co-Chair)
          </li>

          <li>Neil De Young, Hachette Book Group
          </li>

          <li>Linh Do, Random House
          </li>

          <li>Brady Duga, eBook Technologies, Inc.
          </li>

          <li>Geoff Freed, WGBH
          </li>

          <li>Markus Gylling, <del>Daisy</del><ins>DAISY</ins> Consortium
          </li>

          <li>Jonathan Hevenstone, Publishing Dimensions (Working Group Vice Chair)
          </li>

          <li>Rick Johnson, VitalSource Technologies
          </li>

          <li>George Kerscher, <del>Daisy</del><ins>DAISY</ins> Consortium
          </li>

          <li>Steve Kotrch, Simon &amp; Schuster
          </li>

          <li>Bill McCoy, Adobe Systems, Inc.
          </li>

          <li>Jon Noring, Digital Pulp Publishing
          </li>

          <li>Siobhan Padgett, Hachette Book Group
          </li>

          <li>Mina Park, Holtzbrinck Publishers
          </li>

          <li>John Rivlin, eBook Technologies, Inc. (Working Group co-Chair)
          </li>

          <li>Tyler Ruse, CodeMantra
          </li>

          <li>Mike Smith, Harlequin
          </li>

          <li>Peter Sorotokin, Adobe Systems, Inc.
          </li>

          <li>Jennifer Sutton, Benetech
          </li>

          <li>Ben Trafford, Invited Expert
          </li>

          <li>Gary Varnell, Osoft
          </li>

          <li>Eli Willner, Green Point Technology Services
          </li>

          <li>Ric Wright, Adobe Systems, Inc.
          </li>
        </ul>

        <p class="Copy">
          The prior version of the OPS specification, on which this effort is based, was OEBPS 1.2.
          OEBPS 1.2 was developed by the Open eBook Forum Publication Structure Working Group.
          Active members that that working group during development of OEBPS 1.2 were:
        </p>

        <ul class="AuthorList">
          <li>Jeff Alexander, Franklin Electronic Publishers
          </li>

          <li>Garth Conboy, Gemstar eBook Group Limited (Version 1.2 Co-Editor)
          </li>

          <li>Eva Conkright, Random House
          </li>

          <li>Brady Duga, Gemstar eBook Group Limited (Version 1.2 Co-Editor)
          </li>

          <li>Jerry Dunietz, Microsoft Corporation (Working Group Vice Chair)
          </li>

          <li>David Goldstein, Versaware Inc.
          </li>

          <li>Gene Golovchinsky, FX Palo Alto Laboratory, Inc. (Development Sub-Group Co-Chair)
          </li>

          <li>Donald Goyette, McGraw-Hill
          </li>

          <li>Rebecca Guenther, Library of Congress
          </li>

          <li>Markku Hakkinen, isSound Corporation
          </li>

          <li>Barbara Hammond, Nokia
          </li>

          <li>Benjamin Jung, deepX
          </li>

          <li>George Kerscher, <del>Daisy</del><ins>DAISY</ins> Consortium
          </li>

          <li>Christopher R, Maden, crism consulting
          </li>

          <li>Bob Mathews, Adobe
          </li>

          <li>Michael Moodie, National Library Service for the Blind and Physically Handicapped,
          Library of Congress
          </li>

          <li>Jon Noring, Windspun Inc. (Maintenance Sub-Group Chair)
          </li>

          <li>David Pawson, Royal National Institute for the Blind
          </li>

          <li>Chris Powell, University of Michigan Library
          </li>

          <li>James Pritchett, Recording for the Blind and Dyslexic
          </li>

          <li>Allen Renear, Brown University Scholarly Technology Group (Working Group Chair)
          </li>

          <li>Dorothea Salo, OverDrive, Inc. (Working Group Scribe)
          </li>

          <li>Ilan Sender, Microsoft Corporation
          </li>

          <li>Sheela Sethuraman, CAST
          </li>

          <li>Roger Sperberg, e-bks, LLC
          </li>

          <li>Patrick Stickler, Nokia
          </li>

          <li>Lisa Rupe, Questia Media Inc.
          </li>

          <li>Mikhail Vaysbukh, Data Conversion Laboratory
          </li>

          <li>Garret Wilson, GlobalMentor, Inc. (Development Sub-Group Co-Chair)
          </li>

          <li>Harrison Yee, Apex
          </li>
        </ul>
      </div>

      <div class="Section">
        <h2 class="SectionTitle">
          <a class="SectionTitle"
              href="#AppendixTOCD"
              id="AppendixD"
              name="AppendixD">Appendix D: Acknowledgements</a>
        </h2>

        <p class="Copy">
          The working group wishes to specifically acknowledge the contributions of the following
          individuals. <span class="Emphasis">Peter Sorotokin</span> for authoring the OPS and OPF
          RelaxNG schemas, creation of the NVDL definition of OPS, and general technical acumen.
          <span class="Emphasis">Ben Trafford</span> for the concept and drafting of XML Islands,
          as well as overall technical participation, and the XML templates used to produce the
          specifications. <span class="Emphasis">George Kerscher</span> for drafting the OPF NCX
          section, providing consistent accessibility direction and broad technical input.
          <span class="Emphasis">Brady Duga</span> and <span class="Emphasis">Jon Noring</span> for
          directional contributions, specification editing and providing continuity with the
          historic OEBPS 1.2 effort. <span class="Emphasis">Garth Conboy</span> for working group
          leadership and motivation, specification drafting and technical contributions.
        </p>
      </div>

      <div class="Section">
        <h2 class="SectionTitle">
          <a class="SectionTitle"
              href="#AppendixTOCE"
              id="AppendixE"
              name="AppendixE"><ins>Appendix E: Supporting Information &amp; Errata</ins></a>
        </h2>

        <p class="Copy">
          <ins>For additional information about all IDPF specifications including sample files,
          specification implementations and other information, please visit our public forums at
          <a href="http://www.idpf.org/forums"
             target="_blank"
             title="IDPF Forums">http://www.idpf.org/forums</a>. If errors in the specifications
             are identified following publication, please post these errors to the forums. The
             responsible Working Group will review the errors and post pending corrections to the
             specifications if required or necessary. Corrections will be incorporated into
             subsequent versions of the specifications.</ins>
        </p>
      </div>
    </div>
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